In typography, a typeface consists of a coordinated set of glyphs designed with stylistic unity. A typeface usually comprises an alphabet of letters, numerals, and punctuation marks. A typeface may also include ideograms and symbols, or consist entirely of them, for example, mathematical or map-making symbols. The term typeface is often conflated with font, a term which, historically, had a number of distinct meanings prior to the advent of desktop publishing, but is now effectively synonymous with the term font when discussing digital typography.



The art of designing typefaces is called type design, and the people who design them are called type designers?not typographers. Typographers are people who indicate the position the printed word in their design of advertising or bookwork. The typesetter (compositor in hot metal) set the type and then arranged or arranges type in the position indicated.

History of the term font

A font, from Middle French fonte, meaning "(something that has been) melt(ed) [akin to Fondue]" and referring to letters of a typeface produced by casting molten metal at a type foundry, consists of a set of glyphs (images) representing the characters from a particular character set in a particular typeface. Historically, fonts came in specific sizes determining the size of characters, and in quantities of sorts or number of each letter provided. The design of characters in a font took into account all these factors. As the range of typeface designs increased and requirements of publishers broadened over the centuries, fonts of specific weight (blackness or lightness) and stylistic variants?most commonly regular or roman as distinct to italic, as well as condensed) have led to font families, collections of closely-related typeface designs that can include hundreds of styles. A font family is typically a group of related fonts which vary only in weight, orientation, width, etc, but not design. For example, Times is a font family, whereas Times Roman, Times Italic and Times Bold are individual fonts making up the Times family. Font families typically contain several fonts, though some, such as Helvetica, may consist of dozens of fonts. Helvetica, Century Schoolbook, and Courier are examples of three widely distributed typefaces.

English-speaking printers have used the term fount for centuries to refer to the multi-part metal type used to assemble and print in a particular size and typeface. Type foundries have cast fonts in lead alloys from the 1450's until the present, although wood served as the material for some large fonts called wood type during the 19th century, particularly in the United States of America. In the 1890's mechanization typesetting allowed automated casting of fonts on-the-fly as lines of type in the size and length needed. This was known as continuous casting, and remained profitable and widespread until its demise in the 1970's. The first machine of this type was the Linotype invented by Ottmar Mergenthaler.

During a brief transitional period (circa 1950s ? 1990s), photographic technology, known as phototypesetting, produced fonts which came on rolls or discs of film. Photographic typesetting permitted optical scaling, allowing designers to produce multiple sizes from a single font, although physical constraints on the reproduction system used still required design-changes at different sizes?for example, ink traps and spikes to allow for spread of ink encountered in the printing stage. Manually-operated photo-composition systems using fonts on rolls of film allowed fine kerning between letters without the physical effort of manual typesetting, and spawned an enlarged type-design industry in the 1960's and 1970's.

The mid-1970's saw all of the major typeface technologies and all their fonts in use: letterpress, continuous casting machines, phototypositors, computer-controlled phototypesetters, and the earliest digital typesetters?hulking machines with tiny processors and CRT outputs. From the mid-1980s, as digital typography has grown, users have almost universally adopted the American spelling font, which nowadays nearly always means a computer file containing scalable outline letterforms ("digital font"), in one of several common formats. Some fonts, such as Verdana, are designed primarily for use on computer screens.

Digital fonts store the image of each character either as a bitmap in a bitmap font, or by mathematical description of lines and curves in an outline font, also called a vector font. When an outline font is used a rasterizing routine in the application software renders the character outlines, interpreting the vector instructions to decide which pixels should be black and which ones white. Rasterization is straightforward at high resolutions such as those used by laser printers and in high-end publishing systems. For computer screens, where each individual pixel can mean the difference between legible and illegible characters, some digital fonts use hinting algorithms to make readable bitmaps at small sizes.

Digital fonts also contain data representing the metrics used for composition, including kerning pairs, component-creation data for accented characters, glyph-substitution rules for Arabic typography and for connecting script faces, and for simple everyday ligatures like fl. Common description languages that format digital type include METAFONT, PostScript, TrueType and OpenType. Applications using these font formats, including the rasterizers, appear in Microsoft and Apple Computer operating systems, Adobe Systems products and those of several other companies.

Typeface anatomy

Typographers have developed a comprehensive vocabulary for describing the many aspects of typefaces and typography. Some vocabulary applies only to a subset of all scripts. Serifs, for example, are a purely decorative characteristic of typefaces used for European scripts, whereas the glyphs used in Arabic or East Asian scripts have characteristics (such as stroke width) that may be similar in some respects but that can't reasonably be called serifs and that may not be purely decorative.

One can divide many typefaces into two main categories: serif and sans-serif. Serifs comprise the small features at the end of strokes within letters. The printing industry refers to typeface without serifs as sans-serif (from French sans: "without"), or as grotesque (or, in German, grotesk).

Great variety exists among both serif and sans-serif typefaces; both groups contain faces designed for setting large amounts of body text, and others intended primarily as decorative. The presence or absence of serifs forms only one of many factors to consider when choosing a typeface.

Typefaces with serifs are often considered easier to read in long passages than those without. Studies on the matter are ambiguous, suggesting that most of this effect is due to the greater familiarity of serif typefaces. As a general rule, printed works such as newspapers and books almost always use serif typefaces, at least for the text body. Web sites do not have to specify a font and can simply respect the browser settings of the user. But of those web sites that do specify a font, most use modern sans-serif fonts such as Verdana, because it is commonly believed that, in contrast to the case for printed material, sans-serif fonts are easier than serif fonts to read on computer screens due to their lower resolution.

Proportionality

A proportional typeface displays glyphs using varying widths, while a non-proportional or fixed-width or monospace typeface uses fixed glyph widths.

Most people generally find proportional typefaces nicer-looking and easier to read; and thus they appear more commonly in professionally published printed material. For the same reason, GUI computer applications (such as word processors and web browsers) typically use proportional fonts. However, many proportional fonts contain fixed-width figures so that columns of numbers stay aligned.

However, non-proportional typefaces function better for some purposes because their glyphs line up in nice, neat columns. Most non-electronic typewriters and text-only computer displays use only non-proportional fonts. Most computer programs which have a text-based interface (terminal emulators, for example) use only monospace fonts in their configuration. Most computer programmers prefer to use monospace fonts while editing source code.

ASCII art requires a monospace font for proper viewing. In a web page, the HTML tag most commonly specifies non-proportional fonts. In LaTeX, the verbatim environment uses non-proportional fonts.

Any two lines of typical text with the same number of characters in each line in a monospace typeface should display as equal in width, while the same two lines in proportional typeface may have radically different widths. This comes about because wide glyphs (like those for the letters W, Q, Z, M, D, O, H, and U) use more linear space, and narrow glyphs (like those for the letters i, t, l, and 1) use less linear space than the average-width glyph when using a proportional font.

In the publishing industry, editors read manuscripts in fixed-width fonts for ease of editing. The publishing industry considers it discourteous to submit a manuscript in a proportional font.

Measurements

Most scripts share the notion of a baseline: an imaginary horizontal line on which characters rest. In some scripts, parts of glyphs lie below the baseline. The descent spans the distance between the baseline and the lowest descending glyph in a typeface, and the part of a glyph that descends below the baseline has the name "descender". Conversely, the ascent spans the distance between the baseline and the top of the glyph that reaches farthest from the baseline. The ascent and descent may or may not include distance added by accents or diacritical marks.

In the Latin, Greek and Cyrillic scripts, one can refer to the distance from the baseline to the top of regular lowercase glyphs as the x-height, and the part of a glyph rising above the x-height as the "ascender". The height of the ascender can have a dramatic effect on the readability and appearance of a font. The ratio between the x-height and the ascent often serves to characterise typefaces.