For a long time if you had an Apple ID that used a 3rd party email address as your Apple ID you were unable to change it to an Apple @icloud.com email address.
Apple made a change to the way Apple IDs work, and for the first time, Apple customers who have an Apple ID that uses a third-party email address can update that Apple ID to use an Apple @icloud.com, @me.com, or @mac.com email address which will help you streamline your logins and avoid confusion.
Check out this Apple Support Document describing the steps to take to change your Apple iD.
This will NOT change your current email address just the login to Apple services like:
- Apple iD
- Apple store checkout
- App store
If you didn't have one already you will end up with a new email account hosted by Apple iCloud.com. This is an excellent email server that also syncs all the other iCloud services like Notes, Contacts and Calendars.