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A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or one-dimensional (1D), can be scanned by special optical scanners, called
barcode reader A barcode reader is an optical scanner that can read printed barcodes, decode the data contained in the barcode to a computer. Like a flatbed scanner, it consists of a light source, a lens and a light sensor for translating optical impulses into e ...
s, of which there are several types. Later, two-dimensional (2D) variants were developed, using rectangles, dots,
hexagon In geometry, a hexagon (from Ancient Greek, Greek , , meaning "six", and , , meaning "corner, angle") or sexagon (from Latin , meaning "six") is a six-sided polygon or 6-gon creating the outline of a cube. The total of the internal angles of any ...
s and other patterns, called ''matrix codes'' or ''2D barcodes'', although they do not use bars as such. 2D barcodes can be read using purpose-built 2D optical scanners, which exist in a few different forms. 2D barcodes can also be read by a digital camera connected to a microcomputer running software that takes a photographic image of the barcode and analyzes the image to deconstruct and decode the 2D barcode. A
mobile device A mobile device (or handheld computer) is a computer small enough to hold and operate in the hand. Mobile devices typically have a flat LCD or OLED screen, a touchscreen interface, and digital or physical buttons. They may also have a physical k ...
with an inbuilt camera, such as
smartphone A smartphone is a Mobile device, portable computer device that combines Mobile phone, mobile telephone and Mobile computing, computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities ...
, can function as the latter type of 2D barcode reader using specialized
application software An application program (software application, or application, or app for short) is a computer program designed to carry out a specific task other than one relating to the operation of the computer itself, typically to be used by end user, end-user ...
(The same sort of mobile device could also read 1D barcodes, depending on the application software). The barcode was invented by Norman Joseph Woodland and Bernard Silver and patented in the US in 1952. The invention was based on
Morse code Morse code is a method used in telecommunication to Character encoding, encode Written language, text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse cod ...
that was extended to thin and thick bars. However, it took over twenty years before this invention became commercially successful. UK magazine ''
Modern Railways ''Modern Railways'' is a British monthly magazine covering the rail transport industry which was published by Ian Allan Publishing, Ian Allan until March 2012, and Key Publishing since then. It has been published since 1962. The magazine was or ...
'' December 1962 pages 387–389 record how
British Railways British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most of the overground rail transport in Great Britain from 1948 to 1997. It was formed from the nationalisation of the Big Four British ...
had already perfected a barcode-reading system capable of correctly reading rolling stock travelling at with no mistakes. An early use of one type of barcode in an industrial context was sponsored by the
Association of American Railroads The Association of American Railroads (AAR) is an industry trade group representing primarily the major freight Rail transport, railroads of North America (Canada, Mexico and the United States). Amtrak and some regional Commuter rail in North Am ...
in the late 1960s. Developed by General Telephone and Electronics (GTE) and called KarTrak ACI (Automatic Car Identification), this scheme involved placing colored stripes in various combinations on steel plates which were affixed to the sides of railroad rolling stock. Two plates were used per car, one on each side, with the arrangement of the colored stripes encoding information such as ownership, type of equipment, and identification number. The plates were read by a trackside scanner located, for instance, at the entrance to a classification yard, while the car was moving past. The project was abandoned after about ten years because the system proved unreliable after long-term use. Barcodes became commercially successful when they were used to automate supermarket checkout systems, a task for which they have become almost universal. The Uniform Grocery Product Code Council had chosen, in 1973, the barcode design developed by
George Laurer George Joseph Laurer III (September 23, 1925 – December 5, 2019) was an American engineer for IBM at Research Triangle Park in North Carolina. He published 20 bulletins, held 28 patents and developed the Universal Product Code (UPC) in the earl ...
. Laurer's barcode, with vertical bars, printed better than the circular barcode developed by Woodland and Silver. Their use has spread to many other tasks that are generically referred to as automatic identification and data capture (AIDC). The first scanning of the now-ubiquitous
Universal Product Code The Universal Product Code (UPC or UPC code) is a barcode#Symbologies, barcode symbology that is widely used worldwide for tracking trade items in stores. UPC (technically refers to UPC-A) consists of 12 digits that are uniquely assigned to each ...
(UPC) barcode was on a pack of Wrigley's chewing gum in June 1974 at a Marsh supermarket in
Troy, Ohio Troy is a city in and the county seat of Miami County, Ohio, Miami County, Ohio, United States, located north of Dayton, Ohio, Dayton. The population was 26,305 at the 2020 United States census, 2020 census, making it the largest city in Miami Cou ...
, using a scanner made by Photographic Sciences Corporation.
QR code A QR code (an initialism for quick response code) is a type of Barcode#Matrix (2D) barcodes, matrix barcode (or two-dimensional barcode) invented in 1994 by the Japanese company Denso#Denso Wave, Denso Wave. A barcode is a machine-readable optic ...
s, a specific type of 2D barcode, have recently become very popular due to the growth in smartphone ownership. Other systems have made inroads in the AIDC market, but the simplicity, universality and low cost of barcodes has limited the role of these other systems, particularly before technologies such as
radio-frequency identification Radio-frequency identification (RFID) uses electromagnetic fields to automatically Automatic identification system, identify and Tracking system, track tags attached to objects. An RFID system consists of a tiny radio transponder, a radio receiver ...
(RFID) became available after 1995.


History

In 1948 Bernard Silver, a graduate student at
Drexel Institute of Technology Drexel University is a private university, private research university with its main campus in Philadelphia, Pennsylvania. Drexel's undergraduate school was founded in 1891 by Anthony Joseph Drexel, Anthony J. Drexel, a financier and philanthrop ...
in
Philadelphia Philadelphia, often called Philly, is the List of municipalities in Pennsylvania#Municipalities, largest city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, the List of United States cities by population, sixth-largest city i ...
, Pennsylvania, US overheard the president of the local food chain,
Food Fair Food Fair, also known by its successor name Pantry Pride, was a large supermarket chain in the United States. It was founded by Samuel N. Friedland, who opened the first store (as Reading Giant Quality Price Cutter) in Harrisburg, Pennsylvania in ...
, asking one of the deans to research a system to automatically read product information during checkout. Silver told his friend Norman Joseph Woodland about the request, and they started working on a variety of systems. Their first working system used
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
ink, but the ink faded too easily and was expensive. Convinced that the system was workable with further development, Woodland left Drexel, moved into his father's apartment in Florida, and continued working on the system. His next inspiration came from
Morse code Morse code is a method used in telecommunication to Character encoding, encode Written language, text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse cod ...
, and he formed his first barcode from sand on the beach. "I just extended the dots and dashes downwards and made narrow lines and wide lines out of them." To read them, he adapted technology from optical soundtracks in movies, using a 500-watt incandescent light bulb shining through the paper onto an RCA935
photomultiplier A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for sho ...
tube (from a movie projector) on the far side. He later decided that the system would work better if it were printed as a circle instead of a line, allowing it to be scanned in any direction. On 20 October 1949, Woodland and Silver filed a patent application for "Classifying Apparatus and Method", in which they described both the linear and bull's eye printing patterns, as well as the mechanical and electronic systems needed to read the code. The patent was issued on 7 October 1952 as US Patent 2,612,994. In 1951, Woodland moved to IBM and continually tried to interest IBM in developing the system. The company eventually commissioned a report on the idea, which concluded that it was both feasible and interesting, but that processing the resulting information would require equipment that was some time off in the future. IBM offered to buy the patent, but the offer was not accepted.
Philco Philco (an acronym for Philadelphia Battery Company) is an American electronics industry, electronics manufacturer headquartered in Philadelphia. Philco was a pioneer in battery, radio, and television production. In 1961, the company was purchased ...
purchased the patent in 1962 and then sold it to
RCA The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent pool, patent trust owned by General Electric (GE), Westinghouse Electric Corporation, Westin ...
sometime later.


Collins at Sylvania

During his time as an undergraduate, David Jarrett Collins worked at the
Pennsylvania Railroad The Pennsylvania Railroad (reporting mark PRR), legal name The Pennsylvania Railroad Company also known as the "Pennsy", was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. It was named ...
and became aware of the need to automatically identify railroad cars. Immediately after receiving his master's degree from MIT in 1959, he started work at GTE Sylvania and began addressing the problem. He developed a system called ''KarTrak'' using blue and red reflective stripes attached to the side of the cars, encoding a six-digit company identifier and a four-digit car number. Light reflected off the colored stripes was read by
photomultiplier A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for sho ...
vacuum tubes. The
Boston and Maine Railroad The Boston and Maine Railroad was a United States, U.S. Class I railroad in northern New England. Originally chartered in 1835, it became part of what was the Pan Am Railways network in 1983 (most of which was purchased by CSX in 2022). At the ...
tested the KarTrak system on their gravel cars in 1961. The tests continued until 1967, when the
Association of American Railroads The Association of American Railroads (AAR) is an industry trade group representing primarily the major freight Rail transport, railroads of North America (Canada, Mexico and the United States). Amtrak and some regional Commuter rail in North Am ...
(AAR) selected it as a standard, Automatic Car Identification, across the entire North American fleet. The installations began on 10 October 1967. However, the economic downturn and rash of bankruptcies in the industry in the early 1970s greatly slowed the rollout, and it was not until 1974 that 95% of the fleet was labeled. To add to its woes, the system was found to be easily fooled by dirt in certain applications, which greatly affected accuracy. The AAR abandoned the system in the late 1970s, and it was not until the mid-1980s that they introduced a similar system, this time based on radio tags. The railway project had failed, but a
toll bridge A toll bridge is a bridge where a monetary charge (or ''Road pricing, toll'') is required to pass over. Generally the private or public owner, builder and maintainer of the bridge uses the toll to recoup their investment, in much the same way a ...
in
New Jersey New Jersey is a U.S. state, state in the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. It is bordered on the north and east by the state of New York (state), New York; on the ea ...
requested a similar system so that it could quickly scan for cars that had purchased a monthly pass. Then the U.S. Post Office requested a system to track trucks entering and leaving their facilities. These applications required special
retroreflector A retroreflector (sometimes called a retroflector or cataphote) is a device or surface that reflection (physics), reflects radiation (usually light) back to its source with minimum scattering. This works at a wide range of angle of incidence (opt ...
labels. Finally, Kal Kan asked the Sylvania team for a simpler (and cheaper) version which they could put on cases of pet food for inventory control.


Computer Identics Corporation

In 1967, with the
railway Rail transport (also known as train transport) is a means of transport Transport (in British English), or transportation (in American English), is the intentional Motion, movement of humans, animals, and cargo, goods from one location t ...
system maturing, Collins went to management looking for funding for a project to develop a black-and-white version of the code for other industries. They declined, saying that the railway project was large enough, and they saw no need to branch out so quickly. Collins then quit Sylvania and formed the Computer Identics Corporation. As its first innovations, Computer Identics moved from using incandescent light bulbs in its systems, replacing them with
helium–neon laser A helium–neon laser or He-Ne laser, is a type of gas laser whose high energetic medium gain medium consists of a mixture of 10:1 ratio of helium and neon at a total pressure of about 1 torr inside of a small electrical discharge. The best ...
s, and incorporated a mirror as well, making it capable of locating a barcode up to several feet in front of the scanner. This made the entire process much simpler and more reliable, and typically enabled these devices to deal with damaged labels, as well, by recognizing and reading the intact portions. Computer Identics Corporation installed one of its first two scanning systems in the spring of 1969 at a
General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...
(Buick) factory in Flint, Michigan. The system was used to identify a dozen types of transmissions moving on an overhead conveyor from production to shipping. The other scanning system was installed at General Trading Company's distribution center in Carlstadt, New Jersey to direct shipments to the proper loading bay.


Universal Product Code

In 1966, the National Association of Food Chains (NAFC) held a meeting on the idea of automated checkout systems.
RCA The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent pool, patent trust owned by General Electric (GE), Westinghouse Electric Corporation, Westin ...
, who had purchased the rights to the original Woodland patent, attended the meeting and initiated an internal project to develop a system based on the bullseye code. The
Kroger The Kroger Company, or simply Kroger, is an American retail company that operates (either directly or through its subsidiaries) supermarkets and multi-department stores throughout the United States. Founded by Bernard Kroger in 1883 in Cincin ...
grocery chain volunteered to test it. In the mid-1970s, the NAFC established the Ad-Hoc Committee for U.S. Supermarkets on a Uniform Grocery-Product Code to set guidelines for barcode development. In addition, it created a symbol-selection subcommittee to help standardize the approach. In cooperation with consulting firm, McKinsey & Co., they developed a standardized 11-digit code for identifying products. The committee then sent out a contract tender to develop a
barcode system DX (Digital indeX) encoding is an American National Standards Institute, ANSI and I3A standard, originally introduced by Kodak in March 1983, for marking 135 film, 135 and Advanced Photo System, APS photographic film and film cartridges. It consis ...
to print and read the code. The request went to
Singer Singing is the act of creating musical sounds with the voice. A person who sings is called a singer, artist or vocalist (in jazz and/or popular music). Singers perform music (arias, recitatives, songs, etc.) that can be sung accompaniment, wi ...
,
National Cash Register NCR Corporation, previously known as National Cash Register, is an American software, consulting and technology company providing several professional services and Electronics, electronic products. It manufactures Self-checkout, self-service kio ...
(NCR),
Litton Industries Litton Industries was a large defense contractor in the United States named after inventor Charles Litton Sr. During the 1960s, the company began acquiring many unrelated firms and became one of the largest Conglomerate (company), conglomerates ...
, RCA, Pitney-Bowes, IBM and many others. A wide variety of barcode approaches was studied, including linear codes, RCA's bullseye concentric circle code, starburst patterns and others. In the spring of 1971, RCA demonstrated their bullseye code at another industry meeting. IBM executives at the meeting noticed the crowds at the RCA booth and immediately developed their own system. IBM marketing specialist Alec Jablonover remembered that the company still employed Woodland, and he established a new facility in Raleigh-Durham Research Triangle Park to lead development. In July 1972, RCA began an 18-month test in a Kroger store in Cincinnati. Barcodes were printed on small pieces of adhesive paper, and attached by hand by store employees when they were adding price tags. The code proved to have a serious problem; the printers would sometimes smear ink, rendering the code unreadable in most orientations. However, a linear code, like the one being developed by Woodland at IBM, was printed in the direction of the stripes, so extra ink would simply make the code "taller" while remaining readable. So on 3 April 1973, the IBM UPC was selected as the NAFC standard. IBM had designed five versions of UPC symbology for future industry requirements: UPC A, B, C, D, and E. NCR installed a testbed system at Marsh's Supermarket in
Troy, Ohio Troy is a city in and the county seat of Miami County, Ohio, Miami County, Ohio, United States, located north of Dayton, Ohio, Dayton. The population was 26,305 at the 2020 United States census, 2020 census, making it the largest city in Miami Cou ...
, near the factory that was producing the equipment. On 26 June 1974, Clyde Dawson pulled a 10-pack of Wrigley's Juicy Fruit gum out of his basket and it was scanned by Sharon Buchanan at 8:01 am. The pack of gum and the receipt are now on display in the
Smithsonian Institution The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums and education and Research institute, research centers, the largest such complex in the world, created by the Federal government of the United States, U.S. govern ...
. It was the first commercial appearance of the UPC. In 1971, an IBM team was assembled for an intensive planning session, threshing out, 12 to 18 hours a day, how the technology would be deployed and operate cohesively across the system, and scheduling a roll-out plan. By 1973, the team were meeting with grocery manufacturers to introduce the symbol that would need to be printed on the packaging or labels of all of their products. There were no cost savings for a grocery to use it, unless at least 70% of the grocery's products had the barcode printed on the product by the manufacturer. IBM projected that 75% would be needed in 1975. Yet, although this was achieved, there were still scanning machines in fewer than 200 grocery stores by 1977. Economic studies conducted for the grocery industry committee projected over $40 million in savings to the industry from scanning by the mid-1970s. Those numbers were not achieved in that time-frame and some predicted the demise of barcode scanning. The usefulness of the barcode required the adoption of expensive scanners by a critical mass of retailers while manufacturers simultaneously adopted barcode labels. Neither wanted to move first and results were not promising for the first couple of years, with ''Business Week'' proclaiming "The Supermarket Scanner That Failed" in a 1976 article. On the other hand, experience with barcode scanning in those stores revealed additional benefits. The detailed sales information acquired by the new systems allowed greater responsiveness to customer habits, needs and preferences. This was reflected in the fact that about 5 weeks after installing barcode scanners, sales in grocery stores typically started climbing and eventually leveled off at a 10–12% increase in sales that never dropped off. There was also a 1–2% decrease in operating cost for those stores, and this enabled them to lower prices and thereby to increase market share. It was shown in the field that the
return on investment Return on investment (ROI) or return on costs (ROC) is a ratio between net income (over a period) and investment (costs resulting from an investment of some resources at a point in time). A high ROI means the investment's gains compare favourably ...
for a barcode scanner was 41.5%. By 1980, 8,000 stores per year were converting. Sims Supermarkets were the first location in Australia to use barcodes, starting in 1979.


Industrial adoption

In 1981, the
United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an United States federal executive departments, executive branch department of the Federal government of the United States, federal government charged with coordinating and superv ...
adopted the use of Code 39 for marking all products sold to the United States military. This system, Logistics Applications of Automated Marking and Reading Symbols (LOGMARS), is still used by DoD and is widely viewed as the catalyst for widespread adoption of barcoding in industrial uses.


Use

Barcodes are widely used around the world in many contexts. In stores, UPC barcodes are pre-printed on most items other than fresh produce from a
grocery store A grocery store (American English, AE), grocery shop (British English, BE) or simply grocery is a store that primarily retails a general range of food Product (business), products, which may be Fresh food, fresh or Food preservation, packaged ...
. This speeds up processing at check-outs and helps track items and also reduces instances of
shoplifting Shoplifting is the theft of goods from an open retail Retail is the sale of goods and services to consumers, in contrast to wholesaling, which is sale to business or institutional customers. A retailer purchases goods in large quanti ...
involving price tag swapping, although shoplifters can now print their own barcodes. Barcodes that encode a book's
ISBN The International Standard Book Number (ISBN) is a numeric commercial book identifier that is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency. An ISBN is assigned to each separate edition and ...
are also widely pre-printed on books, journals and other printed materials. In addition, retail chain membership cards use barcodes to identify customers, allowing for customized marketing and greater understanding of individual consumer shopping patterns. At the point of sale, shoppers can get product discounts or special marketing offers through the address or e-mail address provided at registration. Barcodes are widely used in the healthcare and hospital settings, ranging from patient identification (to access patient data, including medical history, drug allergies, etc.) to creating SOAP Notes with barcodes to medication management. They are also used to facilitate the separation and indexing of documents that have been imaged in batch scanning applications, track the organization of
species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
in biology, and integrate with in-motion checkweighers to identify the item being weighed in a
conveyor A conveyor system is a common piece of mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transport of heavy or bulky materials. Conveyor systems allow ...
line for
data collection Data collection or data gathering is the process of gathering and measuring information on targeted variables in an established system, which then enables one to answer relevant questions and evaluate outcomes. Data collection is a research com ...
. They can also be used to keep track of objects and people; they are used to keep track of rental cars, airline luggage,
nuclear waste Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, Rare-earth element, rare-earth mining, an ...
,
registered mail Registered mail is a mail service offered by postal services in many countries which allows the sender proof of mailing via a mailing receipt and, upon request, electronic verification that an article was delivered or that a delivery attempt was ...
,
express mail Express mail is an expedited mail delivery service for which the customer pays a premium for faster delivery. Express mail is a service for domestic and international mail, and is in most nations governed by the country's own postal administration ...
and parcels. Barcoded tickets (which may be printed by the customer on their home printer, or stored on their mobile device) allow the holder to enter sports arenas, cinemas, theatres, fairgrounds, and transportation, and are used to record the arrival and departure of vehicles from rental facilities etc. This can allow proprietors to identify duplicate or fraudulent tickets more easily. Barcodes are widely used in shop floor control applications software where employees can scan work orders and track the time spent on a job. Barcodes are also used in some kinds of non-contact 1D and 2D position sensors. A series of barcodes are used in some kinds of absolute 1D
linear encoder A linear encoder is a sensor, transducer or readhead paired with a scale that encodes position. The sensor reads the scale in order to convert the encoded position into an analog signal, analog or digital signal, which can then be decoded into p ...
. The barcodes are packed close enough together that the reader always has one or two barcodes in its field of view. As a kind of fiducial marker, the relative position of the barcode in the field of view of the reader gives incremental precise positioning, in some cases with sub-pixel resolution. The data decoded from the barcode gives the absolute coarse position. An "address carpet", such as Howell's binary pattern and the Anoto dot pattern, is a 2D barcode designed so that a reader, even though only a tiny portion of the complete carpet is in the field of view of the reader, can find its absolute X,Y position and rotation in the carpet. 2D barcodes can embed a
hyperlink In computing, a hyperlink, or simply a link, is a digital reference to Data (computing), data that the user (computing), user can follow or be guided by point and click, clicking or touchscreen, tapping. A hyperlink points to a whole document ...
to a web page. A mobile device with an inbuilt camera might be used to read the pattern and browse the linked website, which can help a shopper find the best price for an item in the vicinity. Since 2005, airlines use an IATA-standard 2D barcode on boarding passes ( Bar Coded Boarding Pass (BCBP)), and since 2008 2D barcodes sent to mobile phones enable electronic boarding passes. Some applications for barcodes have fallen out of use. In the 1970s and 1980s, software source code was occasionally encoded in a barcode and printed on paper ( Cauzin Softstrip and Paperbyte are barcode symbologies specifically designed for this application), and the 1991 '' Barcode Battler'' computer game system used any standard barcode to generate combat statistics. Artists have used barcodes in art, such as Scott Blake's Barcode Jesus, as part of the post-modernism movement.


Symbologies

The mapping between messages and barcodes is called a '' symbology''. The specification of a symbology includes the encoding of the message into bars and spaces, any required start and stop markers, the size of the quiet zone required to be before and after the barcode, and the computation of a
checksum A checksum is a small-sized Block (data storage), block of data derived from another block of digital data for the purpose of error detection, detecting errors that may have been introduced during its telecommunication, transmission or computer ...
. Linear symbologies can be classified mainly by two properties: ; Continuous vs. discrete * Characters in discrete symbologies are composed of ''n'' bars and ''n'' − 1 spaces. There is an additional space between characters, but it does not convey information, and may have any width as long as it is not confused with the end of the code. * Characters in continuous symbologies are composed of ''n'' bars and ''n'' spaces, and usually abut, with one character ending with a space and the next beginning with a bar, or vice versa. A special end pattern that has bars on both ends is required to end the code. ;Two-width vs. many-width * A two-width, also called a binary bar code, contains bars and spaces of two widths, "wide" and "narrow". The precise width of the wide bars and spaces is not critical; typically, it is permitted to be anywhere between 2 and 3 times the width of the narrow equivalents. * Some other symbologies use bars of two different heights ( POSTNET), or the presence or absence of bars ( CPC Binary Barcode). These are normally also considered binary bar codes. * Bars and spaces in many-width symbologies are all multiples of a basic width called the ''module''; most such codes use four widths of 1, 2, 3 and 4 modules. Some symbologies use interleaving. The first character is encoded using black bars of varying width. The second character is then encoded by varying the width of the white spaces between these bars. Thus, characters are encoded in pairs over the same section of the barcode. Interleaved 2 of 5 is an example of this. Stacked symbologies repeat a given linear symbology vertically. The most common among the many 2D symbologies are matrix codes, which feature square or dot-shaped modules arranged on a grid pattern. 2D symbologies also come in circular and other patterns and may employ steganography, hiding modules within an image (for example, DataGlyphs). Linear symbologies are optimized for laser scanners, which sweep a light beam across the barcode in a straight line, reading a ''slice'' of the barcode light-dark patterns. Scanning at an angle makes the modules appear wider, but does not change the width ratios. Stacked symbologies are also optimized for laser scanning, with the laser making multiple passes across the barcode. In the 1990s development of
charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a ...
(CCD) imagers to read barcodes was pioneered by Welch Allyn. Imaging does not require moving parts, as a laser scanner does. In 2007, linear imaging had begun to supplant laser scanning as the preferred scan engine for its performance and durability. 2D symbologies cannot be read by a laser, as there is typically no sweep pattern that can encompass the entire symbol. They must be scanned by an image-based scanner employing a CCD or other digital camera sensor technology.


Barcode readers

The earliest, and still the cheapest, barcode scanners are built from a fixed light and a single
photosensor Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as Photoelectric effect, photoelectric or photoc ...
that is manually moved across the barcode. Barcode scanners can be classified into three categories based on their connection to the computer. The older type is the
RS-232 In telecommunications, RS-232 or Recommended Standard (EIA), Recommended Standard 232 is a technical standard, standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between ...
barcode scanner. This type requires special programming for transferring the input data to the application program. Keyboard interface scanners connect to a computer using a PS/2 or AT keyboard–compatible adaptor cable (a " keyboard wedge"). The barcode's data is sent to the computer as if it had been typed on the keyboard. Like the keyboard interface scanner,
USB Universal Serial Bus (USB) is an technical standard, industry standard that establishes specifications for cables, connectors and communication protocol, protocols for connection, communication and power supply (Interface (computing), interfa ...
scanners do not need custom code for transferring input data to the application program. On PCs running Windows the human interface device emulates the data merging action of a hardware "keyboard wedge", and the scanner automatically behaves like an additional keyboard. Most modern smartphones are able to decode barcode using their built-in camera. Google's mobile Android operating system can use their own Google Lens application to scan QR codes, or third-party apps like Barcode Scanner to read both one-dimensional barcodes and QR codes. Nokia's Symbian operating system featured a barcode scanner, while mbarcode is a
QR code A QR code (an initialism for quick response code) is a type of Barcode#Matrix (2D) barcodes, matrix barcode (or two-dimensional barcode) invented in 1994 by the Japanese company Denso#Denso Wave, Denso Wave. A barcode is a machine-readable optic ...
reader for the
Maemo Maemo is a software platform originally developed by Nokia, now developed by the Free software movement, community, for smartphones and Internet tablets. The platform comprises both the Maemo operating system and Software development kit, SDK. M ...
operating system. In Apple
iOS 11 iOS 11 is the iOS version history, eleventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 10. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers C ...
, the native camera app can decode QR codes and can link to URLs, join wireless networks, or perform other operations depending on the QR Code contents. Other paid and free apps are available with scanning capabilities for other symbologies or for earlier iOS versions. With
BlackBerry The blackberry is an edible fruit produced by many species in the genus ''Rubus'' in the family (biology), family Rosaceae, hybrids among these species within the subgenus ''Rubus'', and hybrids between the subgenera ''Rubus'' and ''Idaeobatus' ...
devices, the App World application can natively scan barcodes and load any recognized Web URLs on the device's Web browser. Windows Phone 7.5 is able to scan barcodes through the
Bing Bing most often refers to: * Bing Crosby (1903–1977), American singer * Microsoft Bing, a web search engine Bing may also refer to: Food and drink * Bing (bread), a Chinese flatbread * Bing (soft drink), a UK brand * Bing cherry, a variety ...
search app. However, these devices are not designed specifically for the capturing of barcodes. As a result, they do not decode nearly as quickly or accurately as a dedicated barcode scanner or portable data terminal.


Quality control and verification

It is common for producers and users of bar codes to have a
quality management system A quality management system (QMS) is a collection of business processes focused on consistently meeting customer requirements and enhancing their satisfaction. It is aligned with an organization's purpose and strategic direction (ISO 9001:2015). I ...
which includes
verification and validation Verification and validation (also abbreviated as V&V) are independent procedures that are used together for checking that a product, service, or system meets requirements and specification (technical standard), specifications and that it fulfi ...
of bar codes. Barcode verification examines scanability and the quality of the barcode in comparison to industry standards and specifications. Barcode verifiers are primarily used by businesses that print and use barcodes. Any trading partner in the
supply chain In commerce, a supply chain is a network of facilities that procure raw materials, transform them into intermediate goods and then final products to customers through a distribution system. It refers to the network of organizations, people, activ ...
can test barcode quality. It is important to verify a barcode to ensure that any reader in the supply chain can successfully interpret a barcode with a low error rate. Retailers levy large penalties for non-compliant barcodes. These chargebacks can reduce a manufacturer's revenue by 2% to 10%. A barcode verifier works the way a reader does, but instead of simply decoding a barcode, a verifier performs a series of tests. For linear barcodes these tests are: * Edge contrast (EC) **The difference between the space reflectance (Rs) and adjoining bar reflectance (Rb). EC=Rs-Rb * Minimum bar reflectance (Rb) **The smallest reflectance value in a bar. * Minimum space reflectance (Rs) **The smallest reflectance value in a space. *Symbol contrast (SC) **Symbol Contrast is the difference in reflectance values of the lightest space (including the quiet zone) and the darkest bar of the symbol. The greater the difference, the higher the grade. The parameter is graded as either A, B, C, D, or F. SC=Rmax-Rmin * Minimum edge contrast (ECmin) **The difference between the space reflectance (Rs) and adjoining bar reflectance (Rb). EC=Rs-Rb * Modulation (MOD) **The parameter is graded either A, B, C, D, or F. This grade is based on the relationship between minimum edge contrast (ECmin) and symbol contrast (SC). MOD=ECmin/SC The greater the difference between minimum edge contrast and symbol contrast, the lower the grade. Scanners and verifiers perceive the narrower bars and spaces to have less intensity than wider bars and spaces; the comparison of the lesser intensity of narrow elements to the wide elements is called modulation. This condition is affected by aperture size. *Inter-character gap **In discrete barcodes, the space that disconnects the two contiguous characters. When present, inter-character gaps are considered spaces (elements) for purposes of edge determination and reflectance parameter grades. * Defects * Decode **Extracting the information which has been encoded in a bar code symbol. * Decodability **Can be graded as A, B, C, D, or F. The Decodability grade indicates the amount of error in the width of the most deviant element in the symbol. The less deviation in the symbology, the higher the grade. Decodability is a measure of print accuracy using the symbology reference decode algorithm. 2D matrix symbols look at the parameters: * Symbol contrast * Modulation * Decode * Unused error correction * Fixed (finder) pattern damage * Grid non-uniformity * Axial non-uniformity Depending on the parameter, each
ANSI The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of Standardization, voluntary consensus standards for products, services, processes, systems, and personnel in the United S ...
test is graded from 0.0 to 4.0 (F to A), or given a pass or fail mark. Each grade is determined by analyzing the scan reflectance profile (SRP), an analog graph of a single scan line across the entire symbol. The lowest of the 8 grades is the scan grade, and the overall ISO symbol grade is the average of the individual scan grades. For most applications a 2.5 (C) is the minimal acceptable symbol grade. Compared with a reader, a verifier measures a barcode's optical characteristics to international and industry standards. The measurement must be repeatable and consistent. Doing so requires constant conditions such as distance, illumination angle, sensor angle and verifier
aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of ray (optics), rays that come to a focus (optics), focus ...
. Based on the verification results, the production process can be adjusted to print higher quality barcodes that will scan down the supply chain. Bar code validation may include evaluations after use (and abuse) testing such as sunlight, abrasion, impact, moisture, etc.


Barcode verifier standards

Barcode verifier standards are defined by the
International Organization for Standardization The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...
(ISO), in ISO/IEC 15426-1 (linear) or ISO/IEC 15426-2 (2D). The current international barcode quality specification is ISO/IEC 15416 (linear) and ISO/IEC 15415 (2D). The European Standard EN 1635 has been withdrawn and replaced by ISO/IEC 15416. The original U.S. barcode quality specification was
ANSI The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of Standardization, voluntary consensus standards for products, services, processes, systems, and personnel in the United S ...
X3.182. (UPCs used in the US – ANSI/UCC5). As of 2011 the ISO workgroup JTC1 SC31 was developing a Direct Part Marking (DPM) quality standard: ISO/IEC TR 29158.


Benefits

In point-of-sale management, barcode systems can provide detailed up-to-date information on the business, accelerating decisions and with more confidence. For example: * Fast-selling items can be identified quickly and automatically reordered. * Slow-selling items can be identified, preventing inventory build-up. * The effects of merchandising changes can be monitored, allowing fast-moving, more profitable items to occupy the best space. * Historical data can be used to predict seasonal fluctuations very accurately. * Items may be repriced on the shelf to reflect both sale prices and price increases. * This technology also enables the profiling of individual consumers, typically through a voluntary registration of discount cards. While pitched as a benefit to the consumer, this practice is considered to be potentially dangerous by privacy advocates. Besides sales and inventory tracking, barcodes are very useful in logistics and supply chain management. * When a manufacturer packs a box for shipment, a Unique Identifying Number (UID) can be assigned to the box. * A database can link the UID to relevant information about the box; such as order number, items packed, quantity packed, destination, etc. * The information can be transmitted through a communication system such as Electronic Data Interchange (EDI) so the retailer has the information about a shipment before it arrives. * Shipments that are sent to a Distribution Center (DC) are tracked before forwarding. When the shipment reaches its final destination, the UID gets scanned, so the store knows the shipment's source, contents, and cost. Barcode scanners are relatively low cost and extremely accurate compared to key-entry, with only about 1 substitution error in 15,000 to 36 trillion characters entered. The exact error rate depends on the type of barcode.


Types of barcodes


Linear barcodes

A first generation, "one dimensional" barcode that is made up of lines and spaces of various widths or sizes that create specific patterns.


Matrix (2D) barcodes

A ''matrix code'', also termed a ''2D barcode'' (although not using bars as such) or simply a ''2D code'', is a two-dimensional way to represent information. It is similar to a linear (1-dimensional) barcode, but can represent more data per unit area.


Example images

File:UPC-A-036000291452.png, GTIN-12 number encoded in UPC-A barcode symbol. First and last digit are always placed outside the symbol to indicate Quiet Zones that are necessary for barcode scanners to work properly File:EAN-13-5901234123457.svg, EAN-13 (GTIN-13) number encoded in EAN-13 barcode symbol. First digit is always placed outside the symbol, additionally right quiet zone indicator (>) is used to indicate Quiet Zones that are necessary for barcode scanners to work properly File:Code93.png, "Wikipedia" encoded in Code 93 File:Code39.png, "*WIKI39*" encoded in Code 39 File:Wikipedia barcode 128.svg, 'Wikipedia" encoded in Code 128 File:Codablock-F Example.png, An example of a ''stacked barcode''. Specifically a "Codablock" barcode. File:Better Sample PDF417.png, PDF417 sample File:Lorem Ipsum.png,
Lorem ipsum In publishing and graphic design, ''Lorem ipsum'' is a placeholder text commonly used to demonstrate the visual form of a document or a typeface without relying on meaningful content. ''Lorem ipsum'' may be used as a placeholder before final C ...
boilerplate text Boilerplate text, or simply boilerplate, is any written text (copy (written), copy) that can be reused in new contexts or applications without significant changes to the original. The term is used about statements, contracts, and computer code, and ...
as four segment
Data Matrix A Data Matrix is a two-dimensional code consisting of black and white "cells" or dots arranged in either a square (geometry), square or rectangle, rectangular pattern, also known as a matrix (mathematics), matrix. The information to be encoded ...
2D File:Azteccodeexample.svg, "This is an example Aztec symbol for Wikipedia" encoded in Aztec Code File:EZcode.png, Text 'EZcode' File:High Capacity Color Barcode.png, High Capacity Color Barcode of the URL for Wikipedia's article on High Capacity Color Barcode File:Dataglyph511140.png, "Wikipedia, The Free Encyclopedia" in several languages encoded in DataGlyphs File:35mm film audio macro.jpg, Two different 2D barcodes used in film:
Dolby Digital Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression (data), audio compression technologies developed by Dolby Laboratories. Formerly named Dolby Stereo Digital until 1995 in film, ...
between the sprocket holes with the "Double-D" logo in the middle, and Sony Dynamic Digital Sound in the blue area to the left of the sprocket holes File:WikiQRCode.png, The
QR Code A QR code (an initialism for quick response code) is a type of Barcode#Matrix (2D) barcodes, matrix barcode (or two-dimensional barcode) invented in 1994 by the Japanese company Denso#Denso Wave, Denso Wave. A barcode is a machine-readable optic ...
for the Wikipedia URL. "Quick Response", the most popular 2D barcode. It is open in that the specification is disclosed and the patent is not exercised. File:MaxiCode.svg, MaxiCode example. This encodes the string "Wikipedia, The Free Encyclopedia" File:Shotcode.png, ShotCode sample File:Twibright Optar Detail Scanned.png, detail of Twibright Optar scan from laser printed paper, carrying 32 kbit/s Ogg Vorbis digital music (48 seconds per A4 page) File:KarTrak code.jpg, A KarTrak railroad Automatic Equipment Identification label on a caboose in Florida


In popular culture

In architecture, a building in Lingang New City by German architects Gerkan, Marg and Partners incorporates a barcode design, as does a shopping mall calle
''Shtrikh-kod''
(Russian for ''barcode'') in Narodnaya ulitsa ("People's Street") in the Nevskiy district of St. Petersburg, Russia. In media, in 2011, the
National Film Board of Canada The National Film Board of Canada (NFB; french: Office national du film du Canada (ONF)) is Canada's public film and digital media producer and distributor. An agency of the Government of Canada, the NFB produces and distributes documentary fi ...
and ARTE France launched a web documentary entitled ''Barcode.tv'', which allows users to view films about everyday objects by scanning the product's barcode with their iPhone camera. In
professional wrestling Professional wrestling is a form of theater that revolves around staged wrestling matches. The mock combat is performed in a ring similar to the kind used in boxing, and the dramatic aspects of pro wrestling may be performed both in the ring or ...
, the WWE stable
D-Generation X D-Generation X (DX) is an American professional wrestling Glossary of professional wrestling terms#Stable, stable, and later a tag team, who consisted of Triple H and Shawn Michaels. The group originated in the World Wrestling Federation (WWF ...
incorporated a barcode into their entrance video, as well as on a T-shirt. In the TV series '' Dark Angel'', the protagonist and the other
transgenics A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, with ...
in the Manticore X-series have barcodes on the back of their necks. In video games, the protagonist of the ''Hitman'' video game series has a barcode tattoo on the back of his head; QR codes can also be scanned in a side mission in '' Watch Dogs''. The 2018 videogame '' Judgment'' features
QR Code A QR code (an initialism for quick response code) is a type of Barcode#Matrix (2D) barcodes, matrix barcode (or two-dimensional barcode) invented in 1994 by the Japanese company Denso#Denso Wave, Denso Wave. A barcode is a machine-readable optic ...
s that protagonist Takayuki Yagami can photograph with his phone camera. These are mostly to unlock parts for Yagami's Drone. In the films '' Back to the Future Part II'' and '' The Handmaid's Tale'', cars in the future are depicted with barcode
licence plate A vehicle registration plate, also known as a number plate (British English), license plate (American English), or licence plate (Canadian English), is a metal or plastic plate attached to a motor vehicle or Trailer (vehicle), trailer for offi ...
s. In the ''Terminator'' films, Skynet burns barcodes onto the inside surface of the wrists of captive humans (in a similar location to the WW2 concentration camp tattoos) as a unique identifier. In music, Dave Davies of
The Kinks The Kinks were an English rock music, rock band formed in Muswell Hill, north London, in 1963 by brothers Ray Davies, Ray and Dave Davies. They are regarded as one of the most influential rock bands of the 1960s. The band emerged during the h ...
released a solo album in 1980, '' AFL1-3603'', which featured a giant barcode on the front cover in place of the musician's head. The album's name was also the barcode number. The April 1978 issue of '' Mad Magazine'' featured a giant barcode on the cover, with the blurb " adHopes this issue jams up every computer in the country...for forcing us to deface our covers with this yecchy UPC symbol from now on!" Interactive Textbooks were first published by ''Harcourt College Publishers to Expand Education Technology with Interactive Textbooks.''


Designed barcodes

Some brands integrate custom designs into barcodes (while keeping them readable) on their consumer products. File:Design Barcode Grasvodka IMG 5574.JPG File:Barcode Tall Horse1.jpg File:Hühner-Bouillon K Designbarcode 4337185009907 IMG 8716.jpg File:Sardinendose K Barcode Art valid IMG11829.jpg File:Barcode_peanut.jpg


Hoaxes about barcodes

There was minor skepticism from conspiracy theorists, who considered barcodes to be an intrusive
surveillance Surveillance is the monitoring of behavior, many activities, or information for the purpose of information gathering, influencing, managing or directing. This can include observation from a distance by means of electronic equipment, such as c ...
technology, and from some Christians, pioneered by a 1982 book ''The New Money System 666'' by Mary Stewart Relfe, who thought the codes hid the number 666, representing the " Number of the Beast".
Old Believers Old Believers or Old Ritualists, ''starovery'' or ''staroobryadtsy'' are Eastern Orthodox Christians who maintain the Liturgy, liturgical and ritual practices of the Russian Orthodox Church as they were before the reforms of Patriarch Nikon of M ...
, a separation of the
Russian Orthodox Church , native_name_lang = ru , image = Moscow July 2011-7a.jpg , imagewidth = , alt = , caption = Cathedral of Christ the Saviour in Moscow, Russia Russia (, , ), or the Russian Fed ...
, believe barcodes are the stamp of the
Antichrist In Christian eschatology, the Antichrist refers to people prophesied by the Bible to oppose Jesus in Christianity, Jesus Christ and substitute themselves in Christ's place before the Second Coming. The Glossary of Christianity, term Antichrist ...
. Television host Phil Donahue described barcodes as a "corporate plot against consumers".


See also

* Automated identification and data capture (AIDC) * Barcode printer * Campus card * European Article Numbering-Uniform Code Council * Global Trade Item Number * Identifier * Inventory control system * Object hyperlinking * Semacode * SMS barcode * SPARQCode (QR code) * List of GS1 country codes


References


Further reading

* ''Automating Management Information Systems: Barcode Engineering and Implementation'' – Harry E. Burke, Thomson Learning, * ''Automating Management Information Systems: Principles of Barcode Applications'' – Harry E. Burke, Thomson Learning, * ''The Bar Code Book'' – Roger C. Palmer, Helmers Publishing, , 386 pages * ''The Bar Code Manual'' – Eugene F. Brighan, Thompson Learning, * ''Handbook of Bar Coding Systems'' – Harry E. Burke, Van Nostrand Reinhold Company, , 219 pages * ''Information Technology for Retail:Automatic Identification & Data Capture Systems'' – Girdhar Joshi,
Oxford University Press Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books ...
, , 416 pages * ''Lines of Communication'' – Craig K. Harmon, Helmers Publishing, , 425 pages * ''Punched Cards to Bar Codes'' – Benjamin Nelson, Helmers Publishing, , 434 pages * ''Revolution at the Checkout Counter: The Explosion of the Bar Code'' – Stephen A. Brown,
Harvard University Press Harvard University Press (HUP) is a publishing house established on January 13, 1913, as a division of Harvard University, and focused on academic publishing. It is a member of the Association of American University Presses. After the retirem ...
, * ''Reading Between The Lines'' – Craig K. Harmon and Russ Adams, Helmers Publishing, , 297 pages * ''The Black and White Solution: Bar Code and the IBM PC'' – Russ Adams and Joyce Lane, Helmers Publishing, , 169 pages * ''Sourcebook of Automatic Identification and Data Collection'' – Russ Adams, Van Nostrand Reinhold, , 298 pages * ''Inside Out: The Wonders of Modern Technology'' – Carol J. Amato, Smithmark Pub, , 1993


External links

* {{Authority control Encodings Automatic identification and data capture 1952 introductions American inventions Records management technology