FLAC is an abbreviation for Free Lossless Audio Codec and is an audio file compression tool that works similarly to the better known mp3 format but without any loss of audio quality. As demands for sound quality increase lossless formats are increasingly replacing lower performing lossy tools.
When a music file is encoded as mp3 there is a definite loss of quality as some important data is lost due to the high degree of compression performed. A FLAC file loses no content, hence the term “lossless”, but still achieves a significant reduction in file size. Like a zip file all the data is retained but, being specifically designed for audio files the resulting file is smaller.
Mp3 files have their place, especially when used with equipment where the optimum sound quality is unattainable, but when audio is played back on high quality, high fidelity hardware the FLAC format is much preferable.
The other great advantage is that FLAC is truly open source, non-proprietary and free of patents. It also has a well documented format and API (Applications Program Interface) and so is very useful to developers.
Similar lossless tools for music file compression are APE, Wavepak and SHN. These are perfectly serviceable but FLAC is the most commonly used.