capitalletters

Capital letters, or uppercase letters, are the larger forms of the letters in an alphabet used in many writing systems. They are typically employed at the beginning of sentences and proper nouns, for acronyms and initialisms, and in titles and headings. In addition, capitalization conventions vary by language and context, but the general purpose is to set apart important elements and aid readability.

Historically, capital letters come from the ancient Roman square capitals used in inscriptions (capitalis), the source of the uppercase forms seen today. The distinction between uppercase and lowercase developed in medieval manuscripts as scribes introduced book hands (minuscule) for faster writing and later typography standardized uppercase and lowercase as separate sets stored in distinct type cases.

In most writing systems, capitalization rules govern when to use capitals: sentence starts, proper nouns (names), institutions, days and months in English and many Western languages, and the initial letters of titles. Some languages capitalize more or less than others; in some contexts, all caps is used for emphasis or for stylistic purposes, though it is often avoided in long blocks of text because it can hinder readability.

In digital text, uppercase and lowercase are encoded as distinct characters in Unicode and ASCII, enabling case-sensitive comparisons and enabling case conversions such as toUpperCase or toLowerCase. Case folding, used for search and normalization, treats letters in a way that may ignore distinctions in some scripts. Capital letters also play a role in branding and typography, where designers may reserve all caps for specific elements.