Free Lossless Audio Codec (FLAC) is a lossless audio format, meaning that although the files are compressed, they maintain their original quality. FLAC files are especially useful for sending music files over the Internet without suffering any sonic loss, as happens with the MP3 format.
Compressing a music file into the MP3 format allows you to send it over the Internet, but making the file smaller sacrifices some of the frequencies and richness of the original recording. A FLAC file is compressed in such a way that it retains the same sound quality as the original.
Waveform audio (WAV) is also a lossless format. However, a song recorded as a WAV file is much larger than the same song recorded as a FLAC file, so it is not useful for sending files via the Internet.
WAV files are an excellent format for storing audio files when you do not have space restrictions. Also, most CD burners can automatically convert the WAV format to the Compact Disk Audio (.cda) format used on standard CDs.
FLAC files will not play on Windows Media Player, iTunes or Quicktime. However, there are many free media players out there such as Winamp, aTunes and Musik that play FLAC and other formats. There are also many programs that let you easily convert FLAC files to WAV, MP3 and other formats. One such program is Trader's Little Helper, which is a free download.