iCloud: iTunes Match
A subscription service that gives you all the benefits of iTunes in the Cloud for music you haven’t purchased from iTunes. iTunes Match lets you store your entire collection, including music you imported from CDs or purchased somewhere other than iTunes for an annual fee.
How it works
iTunes determines which songs in your collection are available in the iTunes Store. Any music with a match is automatically added to your iCloud library for you to listen to anytime, on any device. All the music iTunes matches plays back at 256-Kbps iTunes Plus quality—even if your original copy was of lower quality.
For more information, open iTunes and choose iTunes Help from the Help menu, or visit the iCloud website.