Session ID
In computer science, a session identifier, session ID or session token is a piece of data that is used in network communications (often over HTTPS) to identify a session, a series of related message exchanges. Session identifiers become necessary in cases where the communications infrastructure uses a stateless protocol such as HTTP. For example, a buyer who visits a seller's website wants to collect a number of articles in a virtual shopping cart and then finalize the shopping by going to the site's checkout page.