When Apple's iTunes Radio service launched last year, it was a US-only service. But no more: it's now also available in Australia, which has become only the second market in the world to offer the ad-supported streaming music service.
iTunes Radio is accessed via iTunes, which means it's available on Windows, Mac and iOS devices. It exists in two flavours: an ad-supported version, and an ad-free version available to customers who have paid up $34.99 for iTunes Match, Apple's service for storing your iTunes library in the cloud. If you're a Match subscriber, Apple will also use data about your music purchases to further personalise iTunes Radio playlists.
Its most visible rival is Spotify, which also offers ad-supported streaming. The key differences? Spotify supports multiple mobile platforms (there's no chance iTunes Radio will be offered on Android), and also allows you to select individual tracks or albums. iTunes Radio lets you build "stations" based on a particular track, artist or genre, but you can't directly control what it plays.