1. The set of characters that is handled by a specified machine or allowed by a given programming language or protocol. The set usually includes graphic characters, which denote a printed mark or a space, while control characters produce some particular effect.

Two of the widely used early character sets were ASCII (American standard code for information interchange) and EBCDIC (extended binary coded decimal interchange code). Today most computer systems use Unicode.

2. Any set of symbols used for a particular purpose, not necessarily connected with computing.