iTunes Match is a new feature of iCloud that lets you store all the songs in iCloud – even the ones that you didn’t purchase from iTunes. It scans your music library to find the music that wasn’t purchased from iTunes. Then it matches those songs with the entire iTunes library of Apple to see if they are available for sale in iTunes. If they do, iTunes Match directly adds those songs from iTunes, instead a need for you to upload your songs. As iTunes library is quite vast, there is a big possibility that most of your songs exist in iTunes library, and you just need to upload the songs that do not exist there.
However, iTunes Match is not free. This service costs $24.99 per year, and is available as a part iTunes 10.5 that is coming soon. You can try it by download iTunes 10.5 Beta.
Of course, iCloud or iTunes Match are not the only services that let you store your music on the cloud. If you don’t want to shell out the yearly fee associated with iTunes Match, you can try one of these free cloud music library services that let you store your music library in the cloud.