What are the modes of storing ASP.NET session?

1) InProc: - In InProc mode Session state is stored in the memory space of the Aspnet_wp.exe process. That is the default setting. If the IIS reboots or if web application restarts then session state is lost.

2)State Server:-In StateServer mode Session state is serialized and stored in a separate process (Aspnet_state.exe); therefore, the state can be stored on a distinct computer(a state server).

3)SQL SERVER:- In  the SQL SERVER mode Session state is serialized and stored in a SQL Server database.

The Session state can be specified in element of application configuration file. By Using State Server and SQL SERVER session,  state can be shared across web forms but note this comes at speed cost as ASP.NET require to serialize and deserialize data over network continuously.