iCloud: Apple ID
Your Apple ID is the personal account that gives you access to iCloud. You can also use your Apple ID for other Apple features and services, such as the Apple Online Store, the iTunes Store, and the App Store. You use your Apple ID to sign in to iCloud.com, and you use the same Apple ID to set up iCloud on your iPhone, iPad, iPod touch, Mac, or Windows computer.
If you don’t have an Apple ID yet, you can create one on iCloud.com, in iCloud Settings on your iOS device, or in the iCloud pane of System Preferences on your Mac. Creating an Apple ID on iCloud.com gives you access to iCloud web-only features. You can gain access to all iCloud features by setting up iCloud on your iOS device or Mac.