About FLAC Files
FLAC stands for Free Lossless Audio Codec, a leading compression technique that preserves original audio quality while reducing file size. It is of particular interest to audiophiles who want the highest possible quality of sound. In general, the FLAC option should only be chosen by experts who already know how to deal with the format.
In other words: DO NOT CHOOSE FLAC IF YOU’RE UNFAMILIAR WITH THE FORMAT! We do not offer refunds if you discover afterwards that you don’t know what to do with FLAC files that you’ve downloaded.
FLAC surpasses MP3 quality by preserving the original recording in exact detail. The FLAC format reduces the original file size by roughly 40% with no loss of quality, hence it is referred to as a “lossless” format. In contrast, MP3 compression is “lossy,” meaning that some information is lost in the conversion process. In spite of this, the majority of listeners are unable to tell the difference between a high bitrate MP3, a FLAC version, and the original recording.
One disadvantage of FLAC is that the file size for one of our nature titles will be considerably larger than that of an MP3 version (around 450 megabytes versus 140 megabytes), hence the download time will about three times longer. Also, the user may need to obtain special software in order to play FLAC files or else decode them into uncompressed wave or aiff files for burning CDs (on PCs, the popular Winamp audio player will both play and decode FLAC files).
Go here for a more detailed discussion of FLAC, including software recommendations for various different computer platforms.