iTunes Match determines which songs in your collection and libraries are in the iTunes Store, including ripped-CDs and pirated music, and replaces any content which is found to have better audio quality. iTunes currently downloads music at 256Kbps AAC quality, and music download is DRM-free, allowing you to take your music to any music device, laptop or smartphone.
But even though the service is now available to the public, Apple is still labelling iTunes Match as a 'beta' product, meaning bugs may still be present.
iTunes Match is part of iTunes, and is available for both Mac and Windows users. Mac users can update the software from the 'Software Update' feature, while Windows users can update from the iTunes website or within iTunes itself.