Letter case

Letter case is the distinction between the letters that are in larger uppercase or capitals (more formally majuscule) and smaller lowercase (more formally minuscule) in the written representation of certain languages. The writing systems that distinguish between the upper- and lowercase have two parallel sets of letters: each in the majuscule set has a counterpart in the minuscule set. Some counterpart letters have the same shape, and differ only in size (e.g. ⟨C, c⟩ ⟨S, s⟩ ⟨O, o⟩ ), but for others the shapes are different (e.g., ⟨A, a⟩ ⟨G, g⟩ ⟨F, f⟩). The two case variants are alternative representations of the same letter: they have the same name and pronunciation and are typically treated identically when sorting in alphabetical order.

Letter case is generally applied in a mixed-case fashion, with both upper and lowercase letters appearing in a given piece of text for legibility. The choice of case is often denoted by the grammar of a language or by the conventions of a particular discipline. In orthography, the uppercase is reserved for special purposes, such as the first letter of a sentence or of a proper noun (called capitalisation, or capitalised words), which makes lowercase more common in regular text.

In some contexts, it is conventional to use one case only. For example, engineering design drawings are typically labelled entirely in uppercase letters, which are easier to distinguish individually than the lowercase when space restrictions require very small lettering. In mathematics, on the other hand, uppercase and lowercase letters denote generally different mathematical objects, which may be related when the two cases of the same letter are used; for example, x may denote an element of a set X.

The terms upper case and lower case may be written as two consecutive words, connected with a hyphen (upper-case and lower-case – particularly if they pre-modify another noun), or as a single word (uppercase and lowercase). These terms originated from the common layouts of the shallow drawers called type cases used to hold the movable type for letterpress printing. Traditionally, the capital letters were stored in a separate shallow tray or "case" that was located above the case that held the small letters.

Majuscule (/ˈmædʒəskjuːl/, less commonly /məˈdʒʌskjuːl/), for palaeographers, is technically any script whose letters have no or very few ascenders and descenders (for example, the majuscule scripts used in the Codex Vaticanus Graecus 1209, or the Book of Kells). Consequently, all of the letters of a majuscule script are of roughly the same height and it is written within the space of just two (imaginary or real) parallel lines. This is contrasted with the four lines required by a minuscule script, on which see below. While majuscule scripts were originally used to write entire texts, their letters eventually came to be used primarily with the modern function of uppercase letters in European writing, so the term may sometimes be used as a synonym of 'uppercase letter' or 'capital' in contemporary contexts.

Minuscule refers to lower-case letters. The word is often spelled miniscule, by association with the unrelated word miniature and the prefix mini-. That has traditionally been regarded as a spelling mistake (since minuscule is derived from the word minus), but is now so common that some dictionaries tend to accept it as a non-standard or variant spelling. In paleography, the term refers to a script which includes letters of different heights, with ascenders and descenders, so it needs to be written within a space of four (imaginary or real) parallel lines. Minuscule script letters eventually came to be used with the function of lowercase letters in European writing, which is why the term miniscule is occasionally used to refer to lowercase letters in modern contexts.

The glyphs of lowercase letters can resemble smaller forms of the uppercase glyphs restricted to the baseband (e.g. "C/c" and "S/s", cf. small caps) or can look hardly related (e.g. "D/d" and "G/g"). Here is a comparison of the upper and lower case variants of each letter included in the English alphabet (the exact representation will vary according to the typeface and font used):

(Some lowercase letters have variations e.g. a/ɑ.)