What is an AuthCode and how to I get one?
An AuthCode is officially called an AuthInfo Code, and an Auth-Info code by ICANN and registry operators. It is alternatively called an auth code, a transfer key, a transfer secret, an EPP code, EPP authentication code, or EPP authorization code.
You will need this in order to transfer control of your domain to or from a registrar, or you own direct control (using this site). The controlling registrar is the one you have to go to in order to edit your domain's details or renew its subscription. For NIC.IO you can use this site as your control point and come here to edit your contact details or renew your subscription.
If you domain is managed by a registrar, you will need to request an AuthCode from them.
If you can not obtain an AuthCode from your regsitrar you can take control of the domain yourself using the Owner's password - which can be reset if necessary.
If you manage your domain yourself through the NIC.IO web site, you will need to set the AuthCode yourself.
Login
Click on the My Domains button to go to the list of your domains
Select Set an AuthCode from the drop down to the far right of the corresponding domain name.
For security reasons, all passwords are stored in an encrypted format so it is not possible to reveal the AuthCode in plain text after it has been set.
For the purposes of transfering the domain, either to a registrar or to your own direct control, the Password of the Owner or Admin contact will also work just as well (as an AuthCode) to authorise the transfer. However, regsitrar's usually prefer to use an AuthCode, as this is the industry standard.
AuthCodes are single-use passwords - once the transfer has been completed the AuthCode will be removed. For this reason, it is safer to use an AuthCode when transfering your domain as the AuthCode will be erased once it has been used.