A transfer lock (sometimes called a registrar lock, or clientTransferProhibited status) is a setting that blocks a domain from being transferred to another registrar while it's active. It exists as a straightforward anti-theft measure: without it, anyone who obtained a domain's auth code (see What Is an Auth Code (EPP Code)?) through fraud or a compromised email account could initiate a transfer away with comparatively little friction.

Most registrars, NameBright included, apply this lock by default and recommend leaving it on except during the brief window when you're actually initiating a transfer yourself. This is a concept-level explanation only; the actual toggle location and steps are covered in Unlock a Domain for Transfer.