MP3, which stands for MPEG-1 Audio Layer-3, is a common media format that is used for storing audio data. It works by compressing sound sequence into a tiny file and keeps the original level of sound quality when played. MP3 enables digital storage and transmission, and most music and songs nowadays are shared in .mp3 format. Quality of an MP3 sound can vary based on many factors, such as bitrate, sample rate, joint or normal stereo.