MPEG layer 3 is a type of audio codec where processed by significant compression from the original audio source with very little loss in sound quality. The compression up to 12:1 produces a very little degradation. Tighter compression can be achieved, but it will effect in sound degradation results.

To obtain certain compression, we must adjust the bit rates. The standard bit rates (near CD quality result) is 128 or 112 kbit/s. Many people claim that low-rate MPEG layer 3 files sound better than Real Audio files with similar bit rates.

The advantage of MP3 is that it can be broken up into pieces, and each piece is still playable. The feature that makes this possible - headerless file format - also means that MP3 files can be made to stream across the net real-time (assuming the playback bitrate and speed of the Internet connection are compatible).