Developer: Shazam Entertainment Ltd
App Store Category: Music
Current Version: 1.8.6
Price: free / £2.99
Size: 0.9MB

What is it: Acoustic Fingerprinting application
What's acoustic fingerprinting you might ask? In simple terms, acoustic fingerprinting is the term used to describe how apps like SoundHound and Shazam identify songs based on listening to a snippet and matching them to a database of audio files.

Like that song you can hear on the radio or tv but don't know what it is or who's singing it, whip out your iPhone, start up Shazam and let the app listen to the song for a few seconds (approx. 10 seconds is usually fine) and a few seconds later, the app will tell you the artist, song title, album name and many more details. The latest version of Shazam apparently includes Song Lyrics but I haven't tried that feature yet.
Later versions of Shazam allowed "listening" to be done without an internet connection so that the identification could be done by the app next time you start it up and have an internet connection.

Shazam keeps track of your search history so you can return to previous results at a later time, and it also has direct links to iTunes, Tour Info, YouTube, Artist Biographies, Discographies, similar artists, etc. You can also share results via email, Twitter or Facebook straight from the app itself.

Does it work:

Yes, it works and in my experience has a very good hit rate. Like SoundHound and other similar apps, obscure songs aren't always found but that's most likely because they're missing from the database rather than an issue with the app itself.

Versions:

The free version now has limited tags - 5 free tags per month which is probably enough, I wouldn't use that many. If you got the app before November 2009, you still get unlimited tags with the free version.
The premium version (Shazam Encore) is available with unlimited tags and additional features (faster tagging) and/or no adverts for £2.99.
An iPad optimised version is also available.
A (Shazam)RED version is available for £2.99 with extra features like (RED) News and some proceeds being donated to the (RED) organisations fight against AIDS in Africa.

Verdict:

Fast and stable, easy to use. A great music identification app but like SoundHound, I would only recommend the free version unless you're a heavy user or you want to use this as an opportunity to donate to a worthwhile cause with the (RED) version.

I'll update my review when I've tried out the lyrics feature.

*also posted on ciao.co.uk with the same username*