What is the Auth-code? How do I obtain it?

The Auth-Code, also known as Auth-Info or EEP code, is a password assigned by the registrar as a required security measure when requesting a transfer for domains with extensions .com, .net, .org, .biz, .mobi or .info.

The .es and .eu domains no not have this authorisation code.

If you do not have it you should request it from your current registrar/provider, who will tell you what to do to obtain it. This password is obligatory and necessary in order to request the transfer of your domain.