A credential used to identify a user who has been previously authenticated so that reauthentication is not needed. In Kerberos, the KDC (key distribution center) issues the user a TGT (ticket-granting ticket) when they first authenticate. Thereafter, when they need to access a secure server, they present the ticket-granting ticket to the KDC and are issued a ticket, which they present to the secure server as identification. See also authentication, identification.