This video walks through the process of changing the email address of your Apple ID. Unfortunately you are not able to merge two Apple ID's together, so this is the next best thing.
More often than not, you may have an old email address from an old email provider like Comcast or something else that is your Apple ID.
The problem is that if you were to move or stop using their service, you could have difficultly with your Apple ID account if you were using that email.
In the video I cover examples of changing different Apple ID emails to different email accounts such as iCloud, Gmail, Yahoo and Microsoft Outlook.
