Shazam, if you don't know what it is, (in their own words) is a music discovery engine. If you have ever heard a song playing on the radio and wanted to know what the song was, Shazam can find out for you.

All you do is hold up your iphone or other hand held device to the speaker while the song is playing and in about 20 seconds, it will figure out what song is playing. They claim that it will identify the song despite any background noise.

The first time I saw this, I thought it was amazing. Apparently Shazam has millions of songs in its database that it checks to be able to name the song being played.

But how does Shazam figure out out the song?

What they say is: "When you call in, our system creates a 'fingerprint' of the sound coming in from your mobile and then searches through the 'fingerprint' database for a match."

Actually, the'fingerprint' is fully known as an 'acoustic fingerprint'.

Acoustic fingerprinting is a condensed digital summary, yeilding a unique code generated from an audio waveform, that can be used to identify an audio sample. A computer program compresses the audio signal and figures out the important frequencies and then matches this with a known database.

Another name it can be called is 'media recognition' technology

It was not developed for you to be able to 'name that song', it was developed for labels and media companies to avoid copyright infringement.

So bottom line is that Shazam works by using an acoustic fingerprinting algorithm that figures out the frequencies of the song and then matches it to their database.