Authorization Code
Many domains require an authorization code for a domain transfer between two registrars (providers).
By providing the authorization code, the Domain owner (Reg-C) authorizes the new registrar to begin the transfer. The authorization code makes sure that only an authorized person (domain owner) can move the domain. The domain owner can find the respective authorization code for their domain from their current provider.
Additional Information
If you are having trouble finding your authorization code, please see the following article: