Stateless and Stateful

無狀態

The HTTP Protocol is Stateless！HTTP, the backbone of the WEB, is unable to retain a memory and to identify each client that connects to web site. So... web site treats each request as a unique one, and using independent connection.

                            URL Requests
 Client/Browser   ------------------------------>
 
                  <-----------------------------   Server Side
 
                           HTTP Web Page

有狀態

Cart in E-shop using Session to take memory of the Preprocedure that client did before.Session is protected by Log-in, client shall login firstly, then takes his/her own session in background.