Session State Data
Session state data may be added to the session collection, just as it may be added to the application collection. With the advent of the .NET Framework, a separate process now manages session data. This allows session data to remain intact if IIS shuts down or if the application is hosted on a Web farm or bank of IIS servers.
By default, the session data is managed by a Windows service processalthough it may also be stored in a SQL Server database, in which case a connection string is needed to connect to the appropriate database resource.