In short
The auth code (also AuthInfo) is a security code that authorises a domain transfer. The losing provider supplies it; the gaining provider needs it to take over the domain. Without a valid auth code a regular transfer is not possible.
What the auth code is for
It prevents unauthorised transfers: only someone who knows the code can move a domain to another provider. See also domain transfer.
Requesting the auth code
You get the code in your current provider’s customer area or via their support. Common hosts (incl. IONOS/1&1, Strato, United Domains, Hetzner, GoDaddy, easyname, World4You) provide it in domain management. If your host is not listed, contact their support.
Important
- The auth code is confidential — treat it like a password.
- Some TLDs apply transfer locks for a time after registration/transfer.