Auth code (AuthInfo)
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.
How it differs: the auth code authorises the transfer — it is not a means of payment or a registration.
Example: to move "example.de", you request the auth code from your old provider and enter it with the new one.
Further reading: guide