O2 Tracks is a combination app and music service that lets those based in the UK subscribe to the Official Top 40 music chart and play all the latest hits. The app will automatically download the latest top 40 tracks (and 20 other selected new releases) when the chart is announced each week. These tracks are then available offline (i.e. no streaming) and can be played an unlimited number of times.

The app also includes additional music content that be downloaded and played offline (Just In Playlist, O2 Playlist, etc.) as well as daily celebrity news and gossip. A free trial is available for all UK mobile customers, with a monthly subscription costing £4.99.

O2 Tracks provides an alternative to services such as Spotify, Aupeo, and Nokia Music. The key benefit is that it is based around the top, which means it's ideal for those who want to concentrate on keeping up to date with the latest releases. It's worth noting that its competitors will have the same content (e.g. Nokia Music's UK singles chart mix), but do not have the clear chart classification and top 40 branding tie in.

Windows Phone Store description:

As seen on TV featuring Emeli Sandé , O2 Tracks is THE music app everyone is listening to. Free trial. Open to anyone. Any network.

Get every hit in your pocket with instant access to the Official Top 40, brand new releases and classic tracks updated every day. No streaming. No ads. No data worries. 

O2 Tracks is a free download from the Windows Phone Store. Do note that, after the free trial period, you will need a subscription to use the app. O2 customers get a 8 week free trial and are charged £1 per week (via operator billing). Non-O2 customers get a 2 week trial and are charged £4.99 per month (via credit card, debit card, or PayPal).