typography Typography is the art and technique of Typesetting, arranging type to make written language legibility, legible, readability, readable and beauty, appealing when displayed. The arrangement of type involves selecting typefaces, Point (typogra ...

and

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

, 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 Typeface#Proportion, variable-width fonts, where t ...

characters that may appear on a single line. 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 tha ...

typesetting Typesetting is the composition of text for publication, display, or distribution by means of arranging physical ''type'' (or ''sort'') in mechanical systems or '' glyphs'' in digital systems representing '' characters'' (letters and other ...

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. Init ...

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

typewriter A typewriter is a Machine, mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of Button (control), keys, and each one causes a different single character to be produced on paper by striking an i ...

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. In computer technology, a line of an IBM

punched card A punched card (also punch card or punched-card) is a stiff paper-based medium used to store digital information via the presence or absence of holes in predefined positions. Developed over the 18th to 20th centuries, punched cards were widel ...

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

VT52 The VT50 is a CRT-based computer terminal that was introduced by Digital Equipment Corporation (DEC) in July 1974. It provided a display with 12 rows and 80 columns of upper-case text, and used an expanded set of control characters and forwar ...

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 Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of ''character cells'', ea ...

of the

IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the List of IBM Personal Computer models, IBM PC model line and the basis for the IBM PC compatible ''de facto'' standard. Released on ...

, 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 Printer (computing), prints one entire line of text before advancing to another line. Most early line printers were printer (computing)#Impact printers, impact printers. Line printers are mostly associated with unit record eq ...

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 Computer font#Outline fonts, outline font standardization, standard developed by Apple Inc., Apple in the late 1980s as a competitor to Adobe Inc., Adobe's PostScript fonts#Type 1, Type 1 fonts used in PostScript. It has become the ...

used in

word processing A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features. Word processor (electronic device), Early word processors were stand-alone devices dedicate ...

and

web browsing Web navigation refers to the process of navigating a Computer network, network of web resource, information resources in the International World Wide Web Conference, World Wide Web, which is organized as hypertext or hypermedia. The user interfac ...

, a uniform CPL has been made mostly obsolete.

HTML Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...

(and some other modern text presentation formats) uses dynamic

word wrap Text wrapping, also known as line wrapping, word wrapping or line breaking, is breaking a section of text into lines so that it will fit into the available width of a page, window or other display area. In text display, line wrap is continuing on ...

ping 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 lim ...

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

In programming

Many

style guides A style guide is a set of standards for the writing, formatting, and design of documents. A book-length style guide is often called a style manual or a manual of style. A short style guide, typically ranging from several to several dozen page ...

for

computer programming Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of proc ...

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

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

: With the increasing common use of larger widescreen monitors, some of these limits have been relaxed, as in the Linux kernel and FreeBSD.

References

{{reflist, 30em Text user interface Typography Typesetting

History

In modern computing

In programming

See also

References