Cookies, Sessions, Users and Persistent Information

Due to the nature of the communications mechanisms involved, Web applications do not have automatic or "magic" knowledge about the people or entities accessing them as application users. Moreover, Web applications do not necessarily remember anything about what that user has done before. Due to this behaviour, where every request must tell the application as much as possible for an operation to be carried out, Web applications are referred to as being "stateless".

Yet there are a number of ways of maintaining "state" information - that is, to remember the following things:

Such state information is typically provided using a number of different mechanisms: