Shazam uses a mobile phone's built-in microphone to gather a brief sample of music being played. An acoustic fingerprint<http://en.wikipedia.org/wiki/Acoustic_fingerprint> is created based on the sample, and is compared against a central database for a match. If a match is found, information such as the artist, song title, and album are relayed back to the user. Relevant links to services such as iTunes<http://en.wikipedia.org/wiki/ITunes>, YouTube<http://en.wikipedia.org/wiki/YouTube>, Spotify<http://en.wikipedia.org/wiki/Spotify> or Zune<http://en.wikipedia.org/wiki/Zune> are incorporated into some implementations of Shazam.
How it works[edit<http://en.wikipedia.org/w/index.php?title=Shazam_(service)&action=edit§ion=4>]
Unlike some other services that allow you to identify a song by humming,  Shazam works by analysing the captured sound and seeking a match based on an acoustic fingerprint<http://en.wikipedia.org/wiki/Acoustic_fingerprint> in a database of more than 11 million songs.[10]<http://en.wikipedia.org/wiki/Shazam_(service)#cite_note-10>
Shazam identifies songs based on an audio fingerprint based on a time-frequency graph called a spectrogram<http://en.wikipedia.org/wiki/Spectrogram>.
Shazam stores a catalog of audio fingerprints in a database. The user tags a song for 10 seconds and the application creates an audio fingerprint based on some of the anchors of the simplified spectrogram and the target area between them. For each point of the target area, they create a hash value that is the combination of the frequency at which the anchor point is located, the frequency at which the point in the target zone is located, and the time difference between the point in the target zone and when the anchor point is located in the song.
Once the fingerprint of the audio is created, Shazam starts the search for matches in the database. If there is a match, the information is returned to the user, otherwise it returns an error.[11]<http://en.wikipedia.org/wiki/Shazam_(service)#cite_note-11>
Shazam can identify prerecorded music being broadcast from any source, such as a radio, television, cinema or club, provided that the background noise level is not high enough to prevent an acoustic fingerprint being taken, and that the song is present in the software's database