Session-state allows the retrieval of values for a given user as that user navigates through a website. It is used to maintain state across a visit within the constraints of the stateless HTTP protocol. Session-state is commonly abbreviated to session.
ASP.NET session state supports several different storage options for session data. Each option is identified by a value in the SessionStateMode enumeration. The following list describes the available session state modes:
- InProc mode, which stores session state in memory on the Web server. This is the default.
- StateServer mode, which stores session state in a separate process called the ASP.NET state service. This ensures that session state is preserved if the Web application is restarted and also makes session state available to multiple Web servers in a Web farm.
- SQLServer mode stores session state in a SQL Server database. This ensures that session state is preserved if the Web application is restarted and also makes session state available to multiple Web servers in a Web farm.
- Custom mode, which enables you to specify a custom storage provider.
- Off mode, which disables session state.
You can specify which mode you want ASP.NET session state to use by assigning a SessionStateMode enumeration values to the mode attribute of the sessionState element in your application's Web.config file. Modes other than InProc and Off require additional parameters, such as connection-string values as discussed later in this topic. You can view the currently selected session state by accessing the value of the HttpSessionState.Mode property.
Check more details in the follow link - Session-State Modes
