<Li> ISO / IEC 13818 - 3 </Li> <Tr> <Th> Open format? </Th> <Td> Yes </Td> </Tr> <P> MP3 (formally MPEG - 1 Audio Layer III or MPEG - 2 Audio Layer III) is an audio 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 . </P> <P> MP3 (or mp3) as a file format commonly designates files containing an elementary stream of MPEG - 1 audio and video encoded data, without other complexities of the MP3 standard . </P>

What does mp3 stand for and what is it used for
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