typography Typography is the art and technique of arranging type to make written language legible, readable and appealing when displayed. The arrangement of type involves selecting typefaces, point sizes, line lengths, line-spacing ( leading), an ...

and

computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...

, characters per line (CPL) or terminal width refers to the maximal number of

monospaced A monospaced font, also called a fixed-pitch, fixed-width, or non-proportional font, is a font whose letters and characters each occupy the same amount of horizontal space. This contrasts with variable-width fonts, where the letters and spaci ...

characters that may appear on a single

line Line most often refers to: * Line (geometry), object with zero thickness and curvature that stretches to infinity * Telephone line, a single-user circuit on a telephone communication system Line, lines, The Line, or LINE may also refer to: Art ...

. It is similar to

line length In typography, line length is the width of a block of typeset text, usually measured in units of length like inches or points or in characters per line (in which case it is a measure). A block of text or paragraph has a maximum line length t ...

typesetting Typesetting is the composition of text by means of arranging physical ''type'' (or ''sort'') in mechanical systems or '' glyphs'' in digital systems representing '' characters'' (letters and other symbols).Dictionary.com Unabridged. Random ...

History

The limit of the line length in 70–80 characters may well have originated from various technical limitations of various equipment. The American

teletypewriter A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initi ...

s could type only 72 CPL, while the British ones even less, 70 CPL. In the era of

typewriter A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectivel ...

s, most designs of the typewriter carriage were limited to 80–90 CPL. Standard paper sizes, such as the international standard A4, also impose limitations on line length: using the US standard Letter paper size (8.5×11"), it is only possible to print a maximum of 85 or 102 characters (with the font size either 10 or 12 characters per inch) without margins on the typewriter. With various margins – usually from for each side, but there is no strict standard – these numbers may shrink to 55–78 CPL. Typometer 3

In computer technology, a line of an IBM

punched card A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...

consisted of 80 characters. Widespread computer terminals such as DEC's VT52 and

VT100 The VT100 is a video terminal, introduced in August 1978 by Digital Equipment Corporation (DEC). It was one of the first terminals to support ANSI escape codes for cursor control and other tasks, and added a number of extended codes for special ...

mostly followed this standard, showing 80 CPL and 24 lines. This line length was carried over into the original 80×25 text mode of the

IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team ...

, along with its clones and successors. To this day, virtual terminals most often display 80×24 characters. The "long" line of 132 CPL comes from mainframes'

line printer A line printer prints one entire line of text before advancing to another line. Most early line printers were impact printers. Line printers are mostly associated with unit record equipment and the early days of digital computing, but the ...

s. However, some printers or printing terminals could print as many as 216 CPL, given certain extra-wide paper sizes and/or extra-narrow font sizes.

In modern computing

With the advent of desktop computing and publishing, and technologies such as

TrueType TrueType is an outline font standard developed by Apple in the late 1980s as a competitor to Adobe's Type 1 fonts used in PostScript. It has become the most common format for fonts on the classic Mac OS, macOS, and Microsoft Windows operating ...

used in

word processing A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no conse ...

and web browsing, a uniform CPL has been made mostly obsolete.

HTML The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaS ...

(and some other modern text presentation formats) uses dynamic word wrapping which is more flexible than characters per line restriction and may produce a text block with non-rectangular shape, just like in paper

. Many

plain text In computing, plain text is a loose term for data (e.g. file contents) that represent only characters of readable material but not its graphical representation nor other objects (floating-point numbers, images, etc.). It may also include a limit ...

documents still conform to 72 CPL out of tradition (e.g., ).

In programming

Many style guides for

computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...

define the maximum or desirable number of characters in a line of

source code In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the ...

References

{{reflist, 30em Text user interface Typography Typesetting Wikipedia articles with ASCII art

History

In modern computing

In programming

See also

References