Editing Computer font (section)

{{Short description|Digital description of a typographical font}}
{{More footnotes needed|date=January 2014}}

[[File:Comparison of printed and digital versions of Perpetua.png|thumb|Comparison between printed (top) and digital (bottom) versions of [[Perpetua (typeface)|Perpetua]]]]

A '''computer font''' is implemented as a digital [[data file]] containing a set of graphically related [[glyph]]s. A computer font is designed and created using a [[font editor]]. A computer font specifically designed for the computer screen, and not for printing, is a '''screen font'''.

In the terminology of [[movable type|movable metal type]], a ''[[typeface]]'' is a set of characters that share common design features across styles and sizes (for example, all the varieties of [[Gill Sans]]), while a ''[[font]]'' is a set of pieces of movable type in a specific typeface, size, width, weight, slope, etc. (for example, Gill Sans bold 12 point). In [[HTML]], [[CSS]], and related technologies, the [[Font family (HTML)|font family attribute]] refers to the digital equivalent of a typeface. Since the 1990s, many people outside the printing industry have used the word ''font'' as a [[synonym]] for ''typeface''.

There are three basic kinds of computer font file data formats:
* '''Bitmap''' fonts consist of a matrix of dots or [[pixel]]s representing the image of each glyph in each face and size. This technology is largely obsolete.
* '''Vector''' fonts (including, and sometimes used as a synonym for, '''outline''' fonts) use [[Bézier curve]]s, drawing instructions and mathematical formulae to describe each glyph, which make the character outlines scalable to any size.
* '''Stroke''' fonts use a series of specified lines and additional information to define the size and shape of the line in a specific typeface, which together determines the appearance of the glyph.

Bitmap fonts are faster and easier to create in computer code than other font types, but they are not scalable: a bitmap font requires a separate font for each size.<ref name=Anti-Anti-Aliasing>{{cite web|last1=Gruber|first1=John|title=Anti-Anti-Aliasing|url=http://daringfireball.net/2003/03/anti-anti-aliasing|website=Daring Fireball|access-date=5 September 2015|archive-url=https://web.archive.org/web/20150901034604/https://daringfireball.net/2003/03/anti-anti-aliasing|archive-date=2015-09-01|url-status=live}}</ref> Outline and stroke fonts can be resized in a single font by substituting different measurements for components of each glyph, but they are more complicated to render on screen or in print than bitmap fonts because they require additional computer code to render the bitmaps to display on screen and in print. Although all font types are still in use, most fonts used on computers today are outline fonts.

Fonts can be [[monospaced font|monospaced]] (i.e. every character is plotted a constant distance from the previous character that it is next to while drawing) or [[proportional font|proportional]] (each character has its own width). However, the particular font-handling application can affect the spacing, particularly when [[justification (typesetting)|justifying text]].