In IT Security, a ticket is a number generated by a network server

Server (computing)

In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...

 for a client

Client (computing)

A client is an application or system that accesses a service made available by a server. The server is often on another computer system, in which case the client accesses the service by way of a network....

, which can be delivered to itself, or a different server as a means of authentication

Authentication

Authentication is the act of confirming the truth of an attribute of a datum or entity...

 or proof of authorization

Authorization

Authorization is the function of specifying access rights to resources, which is related to information security and computer security in general and to access control in particular. More formally, "to authorize" is to define access policy...

, and cannot easily be forged. This usage of the word originated with MIT's Kerberos protocol in the 1980s. Tickets may either be transparent, meaning they can be recognized without contacting the server that generated them; or opaque, meaning the original server must be contacted to verify that it issued the ticket.

Some magic cookie

Magic cookie

A magic cookie or just cookie for short, is a token or short packet of data passed between communicating programs, where the data is typically not meaningful to the recipient program. The contents are opaque and not usually interpreted until the recipient passes the cookie data back to the sender...

s provide the same functionality as a ticket.