A specific type of MPEG encoding known formally as MPEG audio layer 3. MP3 uses perceptual audio coding and psychoacoustic compression to remove all superfluous information (more specifically, the redundant and irrelevant parts of a sound signal. The stuff the human ear usually doesn’t hear anyway). The result in real terms is layer 3 shrinks the original sound data from a CD (with a data rate of 1411.2 kilobits per one second of stereo music) by a factor of 12 (down to 112-128kbps) without sacrificing very much sound quality. Proponents of MP3 actually claim there is no sacrifice in sound quality, but audio professionals can usually hear the difference on good equipment. Sound quality is very subjective so each individual’s level of satisfaction with the quality of MP3 encoded recordings is unique. Nevertheless these small files are very easy to transport across the Internet and other mediums that can’t handle huge audio files. MP3 players have become very popular as well. An MP3 player may use a data card, or just have RAM built in for storage and playback of files. Again, because the files are so small (compared to uncompressed audio files) one can hold many, many songs in just a few megabytes of RAM memory, which can be quite convenient.
Due to the convenience and relatively high quality of MP3 files the format has emerged as a standard in the Internet community. Many people routinely pass MP3 encoded material between one another, often in violation of established copyrights. Consequently the RIAA, BMI, ASCAP, and other organizations that represent the rights of artists have taken an active role in trying to control these distribution channels. Lawsuits have ensued and the whole matter is largely up in the air at the time of this writing.