encodingdecoding

Encoding and decoding are processes that convert information from one representation to another for storage, transmission, or processing, and then restore it to its original form. Encoding refers to the transformation into a defined target format, while decoding is the reverse operation performed by a receiver or processor.

Across computing and communications, encoding covers character sets (for example ASCII and UTF-8), data encodings (such as Base64 and URL percent-encoding), and multimedia formats (audio and video codecs like MP3, AAC, and H.264). In networking and data storage, encoding also includes protocols and schemes that prepare data for reliable transfer or efficient storage, including baseband and line coding techniques and various modulation methods used in physical layers.

Encoding is distinct from encryption, which aims to conceal information rather than render it interoperable, and from compression, which reduces data size. Encoding can be lossless or lossy, with lossless encoding allowing full reconstruction and lossy encoding discarding some information for efficiency.

Decoding must be able to reverse the encoding process, but it can be hindered by errors, missing data, or misalignment. To support reliable decoding, systems use metadata, framing, and error detection and correction techniques such as parity checks, checksums, CRCs, and error-correcting codes (for example Reed-Solomon).

Standards and formats define how encoding and decoding should be performed, ensuring interoperability among devices and software.