A character transfer is a paid feature of Battle.net that allows players to move their characters to a new server. All character transfers are final, costing $25, and the full fee must be paid again to undo the move.
There are many restrictions on transferring characters, and each transfer often comes with a wait time until completion. Each character transferred must have empty mailboxes, have no active auctions and cannot be from a starter-edition account. Only specific realms are available at a time to accept new characters, and they change based on population. Additionally, characters cannot be transferred to disabled, frozen or banned accounts.