How to: Save Values in Session State
This example uses the HttpSessionState object to persist values within an individual session.
This example requires:
A Web Forms page or class that has access to the current request context using the Current property in an ASP.NET application that has session state enabled.
Session state can expire (by default, after 20 minutes of inactivity), and the information that you store there can be lost. You can control session-state lifetime using the timeout attribute of the sessionState configuration section.
Depending on your application requirements, you may want to consider an alternative to session state for storing information for each user. ASP.NET provides several other options for persisting data within an application. For a comparison of each, see ASP.NET State Management Recommendations.