How can I protect my domain from being stolen?

all killer.  no filler.

To secure your domain against unauthorized transfers, you can lock your domain. Locking your domain ensures that an authorization code (auth code) cannot be generated for your domain, and the auth code is required to transfer your domain to another service provider. This is a security feature that has been designed to ensure that you have full control over any changes made to your domain.

To lock a domain

  1. Click Manage, and log in to your account.
  2. Beside the domain name, click Transfer Lock.
  3. In the Domain Locking drop-down list, choose Enabled, and then click Save.