MP3 is a popular digital music format for sound files, that are small in size but still reasonably high quality.
This makes it a very suitable format for downloading from the web - audio files can be reduced to around a tenth of their normal size without significant loss of quality. This is achieved by stripping out a lot of the recorded information that our ears aren't able to hear, like the sounds that are outside our hearing range.
If this did not answer your question, please advise what information you would expect to be provided.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.