In server-client architecture, http is a stateless protocol. That means http can't remember from which user the requests are coming to the server. Here every request is treated as a new request. Since http is stateless so we need to maintain the state of user. That means when multiple requests are sending from a particular user(client) to the server then the server is responsible to know that particular user. So in which way the server is knowing or recognizing a particular user, that is session management. So it is a technique in which the server is maintaining the state of an user.
There are four techniques which are used for session management technique, such as: