Google Music, the search giant’s answer to iTunes, has launched in the US.

The new service is designed to be used with Google’s Android operating system for mobile phones and tablet PCs, and will allow users to store up to 20,000 songs in the cloud and stream them to their device for free.

Three of the big four record labels have so far signed up to deliver content to the service – EMI, Sony Music and Universal, but not Warner Music so far.

That means there are millions of songs available to buy via the Android Market, typically priced at 99 cents each. You can hear a 90 second preview of each song before you buy and they’re all downloaded as 320kbps MP3 files, with potentially better sound quality than iTunes’ 256kbps AAC files.

There’s integration with Google-owned YouTube, so if you see a song you like you can buy it easily through Google Music and you can share your tracks with friends via Google+.

To begin with, there are also free tracks available every day “to help jump start your collection” with offerings from the Rolling Stones, Coldplay, Busta Rhymes, Shakira, Pearl Jam and the Dave Matthews Band.

There’s also the option for bands to sign up to the Google Music Artist Hub for $25. This allows them to build their own artist’s page, upload their songs and sell them on the Android Market (they can set their own prices and keep 70 per cent of it).

Google Music is available in the US now in beta version, but there’s no word yet on when it will be coming to the UK.