MPEG-1/2 Audio Layer III, the ubiquitous lossy audio format.
| 0x00000000 | 494433 | ID3 | 'ID3' metadata tag |
Tagless MP3s instead start with an MPEG frame sync: FF followed by a byte with its top 3 bits set.
MP3 is the format that made portable digital music mainstream, using perceptual coding to shrink audio to a fraction of its raw size. Files usually start with an 'ID3' metadata tag; without one, a frame begins with the 11-bit sync pattern FF Ex.
Have a file that might be MP3? Identify it with the File Type Identifier — it reads the magic number locally, nothing is uploaded. Or browse all formats.