Which various modes of storing ASP.NET session?

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

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

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

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