Q: what is  the i tune match

Best to look this up on the main Apple website.

In summary it allows you to synchronise your music across libraries and IOS 5 devices (to a maximum of 10) automatically.  This is achieved by storing your music in the iCloud (remote Apple server) - your Songs will either be 'matched' or 'uploaded' pending the ability of the iTunes Match service to recognise your Song as one that exists in the iTunes Store.

There are several benefits, of which a key one is that 'matched' Songs can be downloaded from the iCloud as 256 kbs AAC files without digital rights management.

Have a look Here

http://support.apple.com/kb/PH2588

and Here

http://support.apple.com/kb/HT4914