FLAC is the acronym for Free Lossless Audio Codec.
FLAC is a free codec allowing the lossless compression of audio files. It implies that your audio files won't lose in terms of quality. The only drawback is that a FLAC file will be still too heavy (about half the size of the original Wave files). Mp3 is one of the most commonly used audio file format. It is ideal for audio streaming and it can be read by most all media players.
There are different programs that can be used to convert FLAC files to MP3 format: