Registrar lock
Registrar lock — the clientTransferProhibited status on a domain — prevents
the domain being transferred to another registrar. It is set by default at most
registrars and costs nothing.
Why its removal matters
A domain hijack has a sequence. Access is gained, the lock is removed, an authorisation code is requested, and the transfer begins. The lock coming off is the earliest step visible from outside — and it is visible, in WHOIS/RDAP, to anyone who looks.
Legitimate removals happen too: you are moving registrar deliberately. The difference is whether you knew.
The related statuses
clientTransferProhibited— set by your registrar. This is the usual lock.serverTransferProhibited— set by the registry, harder to remove, usually for disputes.clientUpdateProhibited/clientDeleteProhibited— block changes and deletion respectively. Worth having on a domain that matters.pendingTransfer— a transfer is already in progress. If you did not start it, act now.
Related
Check any domain's current status with the WHOIS lookup tool. IT Watch alerts at critical severity when transfer lock is removed from a monitored domain, and resolves the alert when it is restored.
See also: Grace period vs redemption period.