Client side state management is way to maintain the application state on client browser. In asp.net you can use following client side state management techniques.
Cookies
You need to store small amounts of information on the client and security is not an issue.
View state
You need to store small amounts of information for a page that will post back to itself. Use of the ViewState property does supply semi-secure functionality.
Hidden fields
You need to store small amounts of information for a page that will post back to itself or another page, and security is not an issue. You can use a hidden field only on pages that are submitted to the server.
Query string
You are transferring small amounts of information from one page to another and security is not an issue.
If you want to keep Web Application state at server end you can try following techniques
Application state object
You are storing infrequently changed, application-scope information that is used by many users, and security is not an issue. Do not store large quantities of information in an application state object.
Session state object
You are storing short-lived information that is specific to an individual session, and security is an issue. Do not store large quantities of information in a session state object. Be aware that a session state object will be created and maintained for the lifetime of every session in your application. In applications hosting many users, this can occupy significant server resources and affect scalability.
Database support
You are storing large amounts of information, managing transactions, or the information must survive application and session restarts. Data mining is a concern, and security is an issue.