lossless compression

A compression technique that decompresses data back to its original form without any loss. The decompressed file and the original are identical. All compression methods used to compress text, databases and other business data are lossless. For example, the ZIP archiving technology (PKZIP, WinZip, etc.) is the most widely used lossless method (see ZIP file).

Lossless vs. Lossy Audio
Audio and video use "lossy" compression, which means bits deemed unnecessary for human hearing or viewing are discarded and never restored. However, for high-quality music listening, there are also lossless audio compression methods. For example, FLAC, Apple Lossless (ALAC) and WMA Lossless compress audio files on a music CD to less than their original size. The resulting files are nowhere near as small as the lossy MP3 and AAC methods but no bits (no frequencies) are discarded. See lossy compression, high-resolution audio, Apple Lossless, WMA Lossless, FLAC and codec examples.