Letterspacing, or tracking, is the uniform adjustment of the space between letters of a font. Not to be confused with kerning.
Definition Letterspacing is the adjustment of the space between letters of a font.
Usage
It is often confused with kerning, which is also concerned with space between letters. But whereas kerning refers to the adjustment of space between pairs of specific letters (such as T and o, which usually require a decrease in the space between them), letterspacing is a uniform adjustment. The same amount of adjustment is applied to all letters (all glyphs, to be precise, as figures and punctuation signs are affected as well). In *TeX, a common tool for letterspacing is the microtype package.
Applications Text set in large type sizes, such as an 18pt heading in a book with 12pt body text, is often given negative, or “tighter” letterspacing: all the letters are brought closer together by a certain amount. Conversely, it is considered good practice to increase letterspacing for text in all capitals. Drastic letterspacing can also be found as a means of adding emphasis to words or short passages of text, in cases where the typeface used does not provide any other means (such as italics). Thus letterspacing used to be common for emphasis in texts produced on typewriters, and it still considered the only appropriate choice when using blackletter typefaces. When using roman type, however, using letterspacing in place of italics for emphasis is a practice frowned upon by typographers.
Letterspacing and Tracking
An alternative term for “letterspacing” is “tracking”. Occasionally, a distinction between the two is made, in which “tracking” is used for a minute adjustment applied to the entire font (in a certain size), whereas “letterspacing” is reserved for referring to the method of emphasis (see above). The microtype package, for example, allows for the adjustment of an entire font's “tracking”, while in addition providing commands for local “letterspacing” for emphasis purposes.
