(1) In programming languages, a single element of a programming language. For example, a token could be a keyword, an operator, or a punctuation mark.
(2) 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. There is only one token for each network, so there is no possibility that two computers will attempt to transmit messages at the same time.