State Management
View state - maintained automatically. each and every control is given a enableviewstate property which is by default true. works when the page is posting back to itself.
Query string - maintained through url. values are passed from one page to the immediately next page by means of modified url. user can easily modify the values in query string
Cookies - maintained by means of small files on the clients machine. user can deny cookies. can manipulate cookies. cookies can go corrupt. secured information cannot be saved in cookies.