In typography, a font (also fount) is traditionally defined as a complete character set of a single size and style of a particular typeface. For example, the set of all characters for 9-point Bulmer italic is a font, and the 10-point size would be a separate font, as would the 9 point upright.

Since the introduction of computer fonts based on fully scalable outlines, a broader definition has evolved. Font is no longer size-specific, but still refers to a single style. Bulmer regular, Bulmer italic, Bulmer bold and Bulmer bold italic are four fonts, but one typeface.

However, the term font is also often used as a metonym for typeface.

Metal type

In a traditional manual printing (letterpress) house the font would refer to a complete set of metal type that would be used to typeset an entire page. Unlike a digital typeface it would not include a single definition of each character, but commonly used characters (such as vowels and periods) would have more physical type-pieces included. A font when bought new would often be sold as (for example in a roman alphabet) 12pt 14A 34a, meaning that it would be a size 12pt fount containing 14 upper-case 'A's, and 34 lower-case 'A's. The rest of the characters would be provided in quantities appropriate for the distribution of letters in that language. Some metal type required in type-setting, such as dashes and line-width spacers, were not part of a specific font in pre-digital usage, but were separate, generic pieces. Line spacing was called "leading", because the lead strips used were made of lead.

In the late 1900s, "hot lead" typesetting was invented, in which type was cast as it was used, either piece by piece (as in the Monotype technology, or entire lines of type at a time (as in the Linotype technology).

Font characteristics

Besides the character height when using the mechanical sense of the term, there are several characteristics which may distinguish fonts, also depending on the script(s) that the typeface supports. In European alphabetic scripts, i.e. Roman, Cyrillic and Greek, the main such properties are the stroke width, called weight, the style or angle and the character width.

Most typefaces are focused on the roman script and hence the regular or standard font is often labeled roman, both to distinguish it from bold or thin and from italic or oblique. The keyword for the default, regular case is often omitted for variants and never repeated, otherwise it would be Bulmer regular italic, Bulmer bold regular and even Bulmer regular regular.

Different fonts of the same face may be used in the same work for various degrees and types of emphasis.

Weight

The weight of a particular font is the thickness of the character outlines relative to their height.