Capitalizations

Capitalization is a writing convention in which the first letter of certain words is written in uppercase. In many languages, capitalization also extends to all-caps contexts used for emphasis, acronyms, or formatting. The system helps signal sentence boundaries, identify proper nouns, and convey formal or stylistic distinctions. Capitalization rules vary by language and register and are enforced by style guides, dictionaries, and typographic standards.

In English, capitalization commonly applies to the first word of a sentence, proper nouns and adjectives that derive from them (for example, London, English), the pronoun I, days of the week, months, and titles of works. In titles, some styles employ title case, which capitalizes major words, while others use sentence case. Abbreviations and acronyms are typically written in uppercase (NASA). In many contexts, capitalization carries conventional meanings and is essential for readability.

Other languages show different patterns. In German, all nouns are capitalized, a feature affecting noun phrases extensively. In French or Spanish, capitalization is more conservative, with only proper nouns and the official names capitalized. Language names themselves are normally capitalized in most languages. Titles and headings follow specific style guides; for instance, Chicago and MLA have distinct rules about which words to capitalize.

Historical note and computing usage: Capital letters originated in uppercase scripts used in classical Latin; lowercase developed in medieval manuscripts. Today, capitalization also serves programming conventions, where constants or macro names are written in uppercase, and some naming schemes use mixed case. In typesetting and digital typography, capitalization affects legibility, emphasis, and the presentation of text in different media.