State management is the process by which you maintain state and page information over multiple requests for the same or different pages. As is true for any HTTP-based technology, Web Forms pages are stateless, which means that they do not automatically indicate whether the requests in a sequence are all from the same client or even whether a single browser instance is still actively viewing a page or site.
Furthermore, pages are destroyed and re-created with each round trip to the server; therefore, page information will not exist beyond the life
cycle of a single page.
ASP.NET includes several options that help you preserve data on both a per-page basis and an application-wide basis.
These features are as follows:
Storing data on the client that is called "Client – Side State Management ".
L View state
L Hidden fields
L Query strings
Store data in memory on the server that is called "Server– Side State Management ".
L Application state
L Session state
L Profile Properties
View state, control state, hidden fields, cookies, and query strings all involve storing data on the client in various ways. However, application state, session state, and profile properties all store data in memory on the server.