What is session?
A session refers to all the connections that a single client might make to a server in the course of viewing any pages associated with a given application. Sessions are specific to both the individual user and the application. As a result, every user of an application has a separate session and has access to a separate set of session variables. A session keeps all of the state that you build up bundled up so that actions you take within your session do not affect any other users connected to other sessions.