Everything you need to know about iTunes Radio, Apple's very own streaming music service
iTunes Radio is Apple's streaming music service. It's available for free with ads to anyone who owns an iPhone or iPad. If you're an iTunes Match subscriber, iTunes Radio is ad-free. Currently iTunes Radio is U.S. only, though it should expand to additional countries in the near future.
With iTunes Radio you can tune in to many of the featured playlists Apple has to offer, which change regularly, or you can create your own custom playlists. Since iTunes Radio is backed by iTunes, one of the largest music databases in the world, music discovery isn't an issue. It may not be as robust and feature packed as on-demand streaming services such as Rdio and Spotify are, but it's one of the best when it comes to curation. People that prefer to buy music rather than rent it will no doubt find a place for iTunes Radio.