Data Compression

Data compression is the process of encoding information using fewer bits than the original representation, exploiting structure, redundancy, or predictability in the source data to reduce storage or transmission costs. It is one of the foundational achievements of Information Theory, inseparable from Claude Shannon's 1948 proof that the entropy of a source sets a hard lower bound on how compactly its messages can be encoded without loss. Every text message sent, every image compressed, every video streamed, and every database query optimized operates within the architecture that data compression established.

The subject divides cleanly into two regimes — lossless and lossy — but the boundary between them is less a technical distinction than a philosophical one about what counts as the