Instead of examining the contents of your iTunes collection and sends a list of your music to Apple. Then ensure Apple to give you access to your music in the "cloud".
18 million songs
Apple has a huge database of more than 18 million music tracks stored in 256 kbps AAC format.
From the list of what music you have in your iTunes collection, and then you get with iTunes Match access to the same pieces of music in the "cloud". If you have music stored in eg. 128 kbps MP3 format, which can even be called excellent quality, so you can then via iTunes Match access the same track, in a very delicate and detailed sound quality.
One of the great advantages of iTunes is to match all your music is stored in 256 kbps AAC format. The format provides excellent audio quality and can be streamed to IOS devices such as iPod or iPhone with ease.
Because all songs are stored in the cloud, then your whole music collection is streamed from the Internet down to your IOS device (iPhone or iPod), wherever you are.
If you want to hear a track or album multiple times or if you do not want to stream all the time, so you can choose to download the music file to your IOS device. iTunes match costs $ 24.99 per year.