In metal typesetting, a font is a particular size, weight and style of a typeface. Each font is a matched set of type, with a piece (a "sort") for each glyph. A typeface consists of various fonts that share an overall design.
In the 21st century, with the advent of computer fonts, the terms "font" and "typeface" are often used interchangeably, although the term "typeface" refers to the design of typographical lettering, whereas the term "font" refers to the specific style of a typeface, such as its size and weight. For instance, the typeface "Bauer Bodoni" (sample shown here) includes fonts "Roman" (or "Regular"), and ; each of these exists in a variety of sizes. The term "font" is correctly applied to any one of these alone but may be seen used loosely to refer to the whole typeface. When used in computers, each style is in a separate digital "font file".
In both traditional typesetting and computing, the word "font" refers to the delivery mechanism of the typeface. In traditional typesetting, the font would be made from metal or wood type: to compose a page may require multiple fonts or even multiple typefaces.
Etymology
The word font (traditionally spelled fount in British English, but in any case pronounced ) derives from Middle French fonte that has been] melted; a casting". The term refers to the process of casting metal type at a type foundry.
Metal type
In a manual printing (letterpress) house the word "font" would refer to a complete set of metal type that would be used to typeset an entire page. Upper- and lowercase letters get their names because of which case the metal type was located in for manual typesetting: the more distant upper case or the closer lower case. The same distinction is also referred to with the terms majuscule and minuscule.
Unlike a digital typeface, a metal font 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 12-point font containing 14 uppercase "A"s, and 34 lowercase "A"s.
The rest of the characters would be provided in quantities appropriate for the distribution of letters in that language. Some metal type characters required in typesetting, such as dashes, spaces and line-height spacers, were not part of a specific font, but were generic pieces that could be used with any font. Line spacing is still often called "leading", because the strips used for line spacing were made of lead (rather than the harder alloy used for other pieces). This spacing strip was made from lead because lead was a softer metal than the traditional forged metal type pieces (which was part lead, antimony and tin) and would compress more easily when "locked up" in the printing "chase" (i.e. a carrier for holding all the type together).
In the 1880s–1890s, "hot lead" typesetting was invented, in which type was cast as it was set, either piece by piece (as in the Monotype technology) or in entire lines of type at one time (as in the Linotype technology).
Characteristics
In addition to the character height, when using the mechanical sense of the term, there are several characteristics which may distinguish fonts, though they would also depend on the script(s) that the typeface supports. In European alphabetic scripts, i.e. Latin, Cyrillic, and Greek, the main such properties are the stroke width, called weight, the style or angle and the character width.
The regular or standard font is sometimes 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. Roman can also refer to the language coverage of a font, acting as a shorthand for "Western European".
Different fonts of the same typeface may be used in the same work for various degrees of readability and emphasis, or in a specific design to make it be of more visual interest.
Weight
The weight of a particular font is the thickness of the character outlines relative to their height.