Token - (In networking) - A token is a special series of bits that travels around a token-ring network. As the token circulates, computers attached to the network can capture it. The token acts like a ticket, enabling its owner to send a message across the network. As there is only one token for each network, there is no possibility (in theory) that two computers will attempt to transmit messages at the same time.  https://en.wikipedia.org/wiki/Token_ring

Token Ring

Security Token