Free Lossless Audio Codec
It’s a means to storing sound data that a computer can read, without any loss of quality (which you would get with mp3 or ogg vorbis).
The Free Lossless Audio Codec, or FLAC, is a type of file format for the compression of audio data. It was originally developed by Josh Coalson and incorporated by Xiphophorus (Xiph.Org Foundation) in 2003. While it is regarded by some as a very popular format, it is in fact much less used than other audio formats such as MP3 and Advanced Audio Coding (AAC). However, in comparison to these two, more popular (and lossy) compression formats, FLAC is totally lossless allowing it to preserve more of the original sound quality of the audio track. Furthermore, FLAC is also able to provide this lossless audio quality without higher file sizes and at a lower bandwidth.
Currently, FLAC can allow audio from a CD or other source to be digitally encoded at a quality that is identical to the original. Even though the file is of high quality, the file size is typically cut in half of what the track would be before compression.
FLAC allows for fast seeking times between tracks when played on a computer based music player. Songs encoded with FLAC can be tagged with a variety of criteria, including artist name, track title, song length, and more. FLAC encoded songs can even support cover art attachments for a full multimedia listening experience.
The other two posters are correct, but it should also be noted that flac produces an audio file this is about 1/2 size as a comparable wav file, but it is still 5-6X larger than a typical 128bit MP3 or Ogg/Vorbis file…
It stands for free lossless audio codec. It is a method of compressing audio files so that they do not lose any quality