the term
Ticket Granting ticket (TGT) ： stored in the CASTGC cookie, represents a SSO session for a user。
Ticket-granting cookie (TGC): It is actually a cookie that contains TGT information.
Service ticket (ST) : A one-time ticket generated by TGT for verification and can only be used once. It is equivalent to the server sending a ticket to the client, and then the client takes this ticket and then goes to the server for verification to see if it is issued by the server.
Web flow diagram
