The service offers several features which integrate with Apple's icloud data storage and access service.
- scans all the music tracks in your Library and makes those songs that are recognized available for streaming and re-download.
- uploads songs that don't exist or match the standard content in Apple's servers so you can re-download and stream those files.
- allows your iOS devices to retrieve music from the cloud rather than a computer with iTunes.
- allows your iOS devices to stream music from the cloud rather than a local computer with iTunes music or home sharing.
- allows your iTunes libraries to re-download tracks from the internet serving as a music backup service while you continue to pay the yearly subscription.
You can read more information about iTunes Match on Apple's iTunes site: