MP3 (or mp3) as a file format commonly designates files containing an elementary stream of MPEG-1 Audio or MPEG-2 Audio encoded data, without other complexities of the MP3 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. 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. MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the US and elsewhere.
