Capitalization

Capitalization, or capitalisation, is writing a word with its first letter as a capital letter (upper-case letter) and the remaining letters in lower case in writing systems with a case distinction. The term is also used for the choice of case in text.

Conventional writing systems (orthographies) for different languages have different conventions for capitalization.

The systematic use of capitalized and uncapitalized words in running text is called "mixed case". Conventions for the capitalization of titles and other classes of words vary between languages and, to a lesser extent, between different style guides.

In some written languages, it is not obvious what is meant by the "first letter": for example, the South-Slavic digraph 'lj' is considered as a single letter for the purpose of alphabetical ordering (a situation that occurs in many other languages) and can be represented by a single Unicode character, but at the start of a word it is written 'Lj': only the L is capitalized. In contrast, in Dutch, when a word starts with the digraph 'ij', capitalization is applied to both letters, such as in the name of the city of IJmuiden. There is a single Unicode character that combines the two letters, but it is generally not used.

The generally accepted rules of capitalization vary between different written languages. The full rules of capitalization for English are complicated. The rules have also changed over time, generally to capitalize fewer terms. To the modern reader, an 18th-century document uses initial capitals excessively. The current rules can be found in style guides, although there is some variation from one guide to another.

Owing to the essentially arbitrary nature of orthographic classification and the existence of variant authorities and local house styles, questionable capitalization of words is not uncommon, even in respected newspapers and magazines. Most publishers require consistency, at least within the same document, in applying a specified standard: this is described as "house style".

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