In orthography and typography, letter case (or just case) is the distinction between majuscule (capital or upper-case) and minuscule (lower-case) letters. The term originated with the shallow drawers called type cases still used to hold the movable type for letterpress printing.
Most occidental languages (certainly those based on the Latin, Cyrillic, Greek and Armenian alphabets) use multiple letter-cases in their written form as an aid to clarity. Scripts using two separate cases are also called "bicameral scripts", while those with only one case are "unicase scripts".
In English, capital letters are used as the first letter of a sentence, a proper noun, or a proper adjective, and for initials or abbreviations. The first-person pronoun "I" and the interjection "O" are also capitalized. Lower-case letters are normally used for all other purposes. There are however situations where further capitalization may be used to give added emphasis, for example in headings and titles or to pick out certain words (often using small capitals). There are also a few pairs of words of different meanings whose only difference is capitalization of the first letter. Other languages vary in their use of capitals. For example, in German the first letter of all nouns is capitalized, while in Romance languages the names of days of the week, months of the year, and adjectives of nationality, religion and so on begin with a lower-case letter.
If an alphabet has case, all or nearly all letters have both a majuscule and minuscule form. Both forms in each pair are considered to be the same letter: they have the same name, same pronunciation, and will be treated identically when sorting in alphabetical order. Languages have capitalization rules to determine whether majuscules or minuscules are to be used in a given context.
An example of a letter without both forms is the German ß (ess-tsett), which exists only in minuscule. When capitalized it normally becomes two letters ("SS"), but the ß letter may be used as a capital to prevent confusion in special cases, such as names. This is because ß was originally a ligature of the two letters "ſs" (a long s and an s), both of which become "S" when capitalized. It later evolved into a letter in its own right. (ß is also occasionally referred to as a ligature of "sz", which recalls the way this consonant was pronounced in some medieval German dialects. The original spelling sz is preserved in Hungarian and pronounced [s].)
Here is a comparison of the majuscule and minuscule versions of each letter used in the English language. The exact representation will vary according to the font used.
The terms upper case and lower case originated in the early days of the printing press used with movable type in letterpress printing. The individual type blocks used in hand typesetting are stored in shallow wooden or metal drawers, known as cases, with subdivisions into compartments known as boxes to store each individual letter. In many countries the majuscules and minuscules are stored separately, with a pair of boxes for each typeface at a specific size. For typesetting, the two cases are taken out of the storage rack and placed on a rack on the compositor's desk. By convention, the case containing the capitals (and small capitals) stands at a steeper angle at the back of the desk, with the case for the small letters, punctuation and spaces, at a shallower angle below it to the front of the desk, hence upper and lower case.
Various patterns of cases are available, often with the compartments for lower-case letters varying in size according to the frequency of use of letters, so that the commonest letters are grouped together in larger boxes at the centre of the case. The compositor takes the letter blocks from the compartments and places them in a composing stick, working from left to right and placing the letters upside down with the nick to the top, then sets the assembled type in a galley.
The Oxford Universal Dictionary on Historical Advanced Proportional Principles (reprinted 1952) indicates that this usage of "case" (as the box or frame used by a compositor in the printing trade) was first used in 1588. Originally one large case was used for each typeface, then "divided cases", pairs of cases for upper and lower case, were introduced in the region of today's Belgium by 1563, England by 1588, and France before 1723. Though pairs of cases were used in English-speaking countries and many European countries in Germany and Scandinavia the single case continued in use.
The distinction between hiragana and katakana in Japanese is similar to, but not the same as, case; it may also be considered analogous to upright and italics characters. While each sound has both a hiragana and katakana, any given word will use only one of the two scripts normally. If a word is written with hiragana, it is not normally considered correct to write it with katakana, and vice versa. However, katakana may be substituted for hiragana or kanji to add emphasis or make them stand out, similar to the use of capitalization or italics in English.
Also similar to case is recent usage in Georgian, where some authors use isolated letters from the Asomtavruli alphabet within a text otherwise written in Mkhedruli in a fashion that is reminiscent of modern usage of letter case in the Latin, Greek, and Cyrillic alphabets.
A variety of styles is used in various circumstances:
In English-language publications, varying conventions are used for capitalizing words in publication titles and headlines, including chapter and section headings. The rules differ substantially between individual house styles. The main examples are (from most to least capitals used):
|The||Vitamins||Are||In||My||Fresh||California||Raisins||"Start case" – capitalization of all words, regardless of the part of speech|
|The||Vitamins||Are||in||My||Fresh||California||Raisins||Capitalization of all words, except for articles, prepositions, and conjunctions|
|The||Vitamins||are||in||My||Fresh||California||Raisins||Capitalization of all words, except for articles, prepositions, conjunctions, and forms of to be|
|The||Vitamins||are||in||my||Fresh||California||Raisins||Capitalization of all words, except for closed-class words|
|The||Vitamins||are||in||my||fresh||California||Raisins||Capitalization of all nouns|
|The||vitamins||are||in||my||fresh||California||raisins||Sentence case – Capitalization of only the first word, proper nouns and as dictated by other specific English rules|
|the||vitamins||are||in||my||fresh||California||raisins||Mid-sentence case – capitalization of proper nouns only|
|the||vitamins||are||in||my||fresh||california||raisins||All-lowercase letters (unconventional in formal English)|
Among U.S. book publishers (but not newspaper publishers), it is a common typographic practice to capitalize "important" words in titles and headings. This is an old form of emphasis, similar to the more modern practice of using a larger or boldface font for titles. Most capitalize all words except for closed-class words, or articles, prepositions and conjunctions. Some capitalize longer prepositions such as "between", but not shorter ones. Some capitalize only nouns, others capitalize all words. This family of typographic conventions is usually called title case. Of these various styles, only the practice of capitalizing nouns, pronouns, verbs, adverbs and adjectives but not articles, conjunctions or prepositions (though some styles except long prepositions) is considered correct in formal American English writing, according to most style guides, though others are found in less formal settings.
The convention followed by many British publishers (including scientific publishers, like Nature, magazines, like The Economist and New Scientist, and newspapers, like The Guardian and The Times) is to use sentence-style capitalization in titles and headlines, where capitalization follows the same rules that apply for sentences. This convention is sometimes called sentence case. It is also widely used in the United States, especially in newspaper publishing, bibliographic references and library catalogues. Examples of global publishers whose English-language house styles prescribe sentence-case titles and headings include the International Organization for Standardization.
In creative typography, such as music record covers and other artistic material, all styles are commonly encountered, including all-lowercase letters and mixed case (StudlyCaps).
One British style guide mentions a form of title case: R.M. Ritter's "Oxford Manual of Style" (2002) suggests capitalizing "the first word and all nouns, pronouns, adjectives, verbs and adverbs, but generally not articles, conjunctions and short prepositions".
Some sentence cases are not used in standard English, but are common in computer programming, as well as in product branding and in other specialised fields:
The conversion of letter case in a string is common practice in computer applications, for instance to make case-insensitive comparisons. Many high-level programming languages provide simple methods for case folding, at least for the ASCII character set.
In some forms of BASIC there are two methods for case folding:
UpperA$ = UCASE$("a") LowerA$ = LCASE$("A")
char upperA = toupper('a'); char lowerA = tolower('A');
#define toupper(c) (islower(c) ? (c) - 'a' + 'A' : (c)) #define tolower(c) (isupper(c) ? (c) - 'A' + 'a' : (c))
This only works because the letters of upper and lower cases are spaced out equally. In ASCII they are consecutive, whereas with EBCDIC they are not; nonetheless the upper case letters are arranged in the same pattern and with the same gaps as are the lower case letters, so the technique still works.
Some computer programming languages offer facilities for converting text to a form in which all words are first-letter capitalized. Visual Basic calls this "proper case"; Python calls it "title case". This differs from usual title casing conventions, such as the English convention in which minor words are not capitalized.
Unicode defines case folding through the three case-mapping properties of each character: uppercase, lowercase and titlecase. These properties relate all characters in scripts with differing cases to the other case variants of the character.
As briefly discussed in Unicode Technical Note #26, "In terms of implementation issues, any attempt at a unification of Latin, Greek, and Cyrillic would wreak havoc [and] make casing operations an unholy mess, in effect making all casing operations context sensitive [...]". In other words, while the shapes of letters like A, B, E, H, K, M, O, P, T, X, Y and so on are shared between the Latin, Greek, and Cyrillic alphabets (and small differences in their canonical forms may be considered to be of a merely typographical nature), it would still be problematic for a multilingual character set or a font to provide only a single codepoint for, say, uppercase letter B, as this would make it quite difficult for a wordprocessor to change that single uppercase letter to one of the three different choices for the lower case letter, b (Latin), β (Greek), or в (Cyrillic). Without letter case, a 'unified European alphabet'—such as ABБCГDΔΕZЄЗFΦGHIИJ...Z, with an appropriate subset for each language—is feasible; but considering letter case, it becomes very clear that these alphabets are rather distinct sets of symbols.