A de facto standard is a custom or convention
that has achieved a dominant position by public acceptance or market forces (for example, by early entrance to the market
). is a Latin phrase that means
''in fact'' (literally by or from fact) in the sense of "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established", as opposed to de jure
The term de facto standard is used in contrast with obligatory standards (also known as "de jure standards"); or to express the dominant voluntary standard, when there is more than one standard available for the same use.
In social sciences
, a voluntary standard that is also a de facto standard is a typical solution to a coordination problem
The choice of a ''de facto'' standard tends to be stable in situations in which all parties can realize mutual gains, but only by making mutually consistent decisions. In contrast, an enforced "de jure standard" is a solution to the prisoner's problem
A selection of well-known and illustrative examples of de facto and de jure standards are:
* with consolidation by tradition of use
** The driver's seat side
in a given country starts as a user/industry preference, turning to a local tradition, then a traffic code local norm
** The QWERTY
system was one of several options for the layout of letters on typewriter
(and later keyboard
) keys. It became a de facto standard because it was used on the most commercially successful early typewriters and is now used on devices which have no moving parts such as touchscreen
** The MP3
audio format started as an alternative to WAV
for Internet music distribution, then replaced it — it is now supported by the vast majority of music players, audio transport
, audio storage
and noncommercial media. WAV and MP3 are also "de jure ISO formats".
* with consolidation by uniqueness and efficiency:
(computer file format) started as "de facto" (1993-1995) and became the "de jure" standard (1995–present day).
(computer file format) was first created in 1993 by Adobe
. Adobe internal standards were part of its software quality
systems, but they were neither published nor coordinated by a standards body. With the Acrobat Reader
program available for free, and continued support of the format, PDF eventually became the de facto standard for printable documents. In 2005, PDF/A
became a de jure standard
19005-1:2005. In 2008 Adobe's PDF 1.7 became ISO
Examples of long-time de facto but never de jure standards (for computer file formats):
* AutoCAD DXF
: a de facto ASCII format
for import and export of CAD
drawings and fragments in the 1980s and 1990s. In the 2000s, XML
based standards emerged as de facto standards.
(over all other old PC word processors
): one of the best known de facto standards. Due to the market dominance of Word, it is supported by all office applications that intend to compete with it, typically by reverse engineering
the undocumented file format. Microsoft has repeatedly internally changed the file specification between versions of Word to suit their own needs, while continuing to reuse the same file extension identifier for different versions.
file formats, commonly used in science and engineering, with FITS traditionally used in astronomy
typesetting system, commonly used in creating scientific articles and reports for publication (in fact many journals require the publication to be fully written in TeX).
* Most American-made spark plugs
require a -inch hex socket (21mm) to remove or install.
* The spacing of the rollers in a bicycle chain
* The IBM Personal Computer
(PC). By one year after its 1981 release, John Dvorak
described the PC as rapidly becoming a "de facto standard microcomputer".
With the MS-DOS
and Microsoft Windows operating system
s, it gained a large share of the personal computer market. Because of the great influence of the IBM PC on the personal computer market
, competing products like the Rainbow 100
were eventually withdrawn.
* Interpreted programming languages such as PHP
that have multiple implementations tend to also have a de facto standard. In PHP's case the de facto standard is the binaries available from php.net, rather than the Phalanger
implementation for example.
* Use of programming languages R
in data science and other science disciplines, other than computer science, where automated analysis of data is required, without system being too complicated for a persons not being professionals.
Various connectors and interconnect standards - despite being formalized and standardized, almost no product is required by law or other legal standard to use them. Examples:
* Phone connector
(3.5mm jack), RCA
connectors, used in audio industry, for connecting audio equipment, headphones, mixing consoles, microphones (often with phantom power
with 48 volts in most applications), stage lighting, etc.
connection (using so called DIN connector
), electrical and protocol standard for connecting musical instruments, synthesizers, drum machines, sequencers and some audio equipment, as well daisy chaining
(commonly just DMX) with XLR connector
to control and sometimes power stage and venue lights, effects, smoke machines, laser projectors and sometimes pyrotechnics.
* PCI Express
electrical and mechanical interface, and interconnect protocol used in PC computers, desktops, laptops, server, and industrial applications.
, also known as IEEE-488
, multi-device bus protocol, mechanical and electronic interface commonly found in electronic test equipment, i.e. digital multimeter
s, initially created by Hewlett Hewlett-Packard
as HP-IP. Commonly used with SCPI
, Display Port
for video, RS-232
for low bandwidth serial communication.
for high speed serial interface in computers and for powering or charging low power external devices (like mobile phones, headphones, portable hard drives) usually using micro USB plug and socket.
* Banana plugs
in low frequency voltage and current measurements.
for medium frequency signal in electronic engineering testing (commonly used by signal generators, oscilloscopes, advanced multimeters and LCR meter
s, vector network analysers
) and sometimes in video signal (analog and digital) delivery between devices in studios and other professional settings.
's AMP MATE-N-LOK / Molex
's Standard .093" Pin Power plug and socket, commonly used on hard drives, and other medium power devices both in PC, server, industrial applications, and others where standardized power connector for 5V and 12V is required, and off the shelf PSU
can be used. In embedded applications it is usually replaced with smaller square connector, that is easier to connect.
* 2.54mm (0.1 inch) pin spacing on many electronic components, including DIP
packages, header connector
s, and many more. The standard spacing enable use of these devices in prototyping boards and standardized sockets.
current loop standard used by sensors, transducers, amplifiers, transmission lines, control and measurement equipment.
* 3.5 inch and 2.5 inch (actual dimensions are different) hard drive standard sizes.
* 19-inch rack
standards for telecommunication, server, storage, audio, music, video and power equipment.
motherboard, back plane and power standards (but the intention of ATX design was to reduce number of standards, so it was not established by convention, but by biggest PC hardware and components manufacturers at the time).
* many more connectors and cables, like standardized ribbon cables medium speed and power connection between boards and devices; use of RJ45 jack
in Ethernet switches for management purposes (instead of another de facto standard, RS-232
connector); SD and microSD cards for removable storage in mobile applications like photo cameras, video recorders, phones; AA batteries
Materials and units of packaging:
* Soldering alloys
in electronics, like Sn60Pb40.
* Aluminium alloy
s, with most common being 6061
* Volumes, weights and quantities of common consumables usually follow round number of base legal units, i.e. in Europe milk is usually sold in 1 liter containers, and eggs are sold as quantity of 6.
There are many examples of de facto consolidation (of a standard) by market forces and competition
, in a two-sided market
, after a dispute
* Alternating current
over direct current
: see War of the currents
(see videotape format war
): when the VHS format for videotape
recording was introduced, other recording formats were already available in the market. Regardless of whether Betamax was superior from a technical point of view or not, the VHS format won the format war
due to superior marketing tactics by its proponents. The market could not support two competing formats; VHS became the de facto standard and Betamax was eventually withdrawn.
over HD DVD
(see high definition optical disc format war
* Scalable Vector Graphics
(SVG) over Adobe Flash
(ceasing development in 2020) for vector graphics web page animation
Examples of standards that are "in dispute" for turns de facto:
format (a de facto standard for Linux
users (Apache OpenOffice
et al. use it as default file format)) ''vs'' Microsoft's Office Open XML
format (a de facto standard for MS-Windows
and Mac users).
* Dominant design
* Free market
* Format war
* Real versus nominal value
* Embrace, extend, and extinguish