FLAC stands for Free Lossless Audio Codec.
by encoding audio files with FLAC, the quality is exactly the same as the original audio file's quality is. This is exactly unlike the audio formats such as MP3 and WMA work -- these audio formats are called "lossy" and that means that when the original audio is encoded into the lossy audio format, some of the audio data is lost forever and can't be brought back by any means.
FLAC stands for Free Lossless Audio Codec. FLAC is a popular audio compression codec that is lossless. Unlike lossy codecs such as MP3 and AAC, it does not remove any information from the audio stream and is suitable both for everyday playback and for archiving audio collections. The FLAC format is currently well supported by many software and hardware audio products.
On January 29th, 2003, Xiphophorus (now called the Xiph.Org Foundation) announced the incorporation of FLAC under their Xiph.Org banner, to go along with Ogg Vorbis, Ogg Theora, and Speex.