Codage

Codage is the process of converting information into a standardized form for storage, processing, or transmission. In computing and communications, codage encompasses encoding data into machine-readable formats, applying character sets for text, and organizing data so that it can be reliably decoded later. It is related to, but distinct from, encryption, which aims to hide meaning rather than enable decoding by authorized parties.

Character encodings, such as ASCII and Unicode (UTF-8), define how characters are represented as binary data and how sequences of bytes map to characters. Encoding choices influence interoperability, text processing, storage efficiency, and the handling of cultural variations. Endianness, normalization, and error detection in text streams are practical issues within codage.

Data compression and coding theory address reducing information size and ensuring reliable communication. Lossless encodings (ZIP, PNG) preserve exact data, while lossy encodings (MP3, JPEG) trade some information for smaller size. In coding theory, error detection and correction codes (parity bits, CRC, Reed–Solomon) protect data against corruption in storage or transmission.

Codage also covers channel and line coding, modulation schemes, and other techniques used to transmit encoded data over physical media. Standards bodies such as ISO, ANSI, and ITU define codage formats to promote interoperability across devices and networks.

Historically, codage evolved from early telecommunication methods to modern digital representations. The development of ASCII, Unicode, and information theory by Claude Shannon formalized how information can be efficiently encoded, transmitted, and decoded.