A Windows Live ID is the email address and password you use to sign in to any of the following: Xbox LIVE Zune Hotmail MSN Messenger Find My Phone OneDrive (formerly SkyDrive)
Once you've created a Windows Live ID—and you may have done so without even realizing it—you can use it to buy apps, games, or music on Marketplace, play Xbox LIVE games, use Messenger and Facebook Chat, add Twitter and LinkedIn accounts to your People Hub, use a Zune Music Pass, and more.
You can use any email address you want to create a Windows Live ID. If you don't have a Windows Live ID, we'll walk you through creating one when you sign in on your phone. Or you can create one at www.live.com.