FLAC stands for Free Lossless Audio Codec. Grossly oversimplified, FLAC is similar to Ogg Vorbis, but lossless. The FLAC project consists of the stream format, reference encoders and decoders in library form, flac, a command-line program to encode and decode FLAC files, metaflac, a command-line metadata editor for FLAC files and input plugins for various music players.