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An Apple ID is a user name you use for everything you do with Apple. Creating an account for an Apple service, such as the iTunes Store or the App Store, creates an Apple ID. Apple ID allows you to access other Apple services. You don't have to create a new account for each service—just use your Apple ID.
You can change your Apple ID Name at My Apple ID. Click on Manage your Apple ID and sign in with your Apple ID name and password. Click Edit and enter the new information, then click Save Changes. Changes take effect immediately. You can also use My Apple ID to change your personal information, such as your mailing address or email address. See Changing the name you use for your Apple ID if you'd like more information.