Wikipedia quote: "MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III)[4] is a coding format for digital audio. Originally defined as the third audio format of the MPEG-1 standard, it was retained and further extended—defining additional bit-rates and support for more audio channels—as the third audio format of the subsequent MPEG-2 standard. A third version, known as MPEG 2.5—extended to better support lower bit rates—is commonly implemented, but is not a recognized standard." 

Wikipedia article: https://en.wikipedia.org/wiki/MP3

Media Player software article: https://en.wikipedia.org/wiki/Media_player_software

Comparison of audio player software: https://en.wikipedia.org/wiki/Comparison_of_audio_player_software

Pmusic by zigbert - native Puppy Linux audio player: http://murga-linux.com/puppy/viewtopic.php?search_id=1411526182&t=31206
													 http://wikka.puppylinux.com/pmusic