Types of sessions:

• InProc: The default way to use sessions. InProc is the fastest way to store and access sessions.
• OutProc:
  i. State server: 15% slower than InProc. Session is serialized and stored in aspnet_state.exe process. Stateserver sessions can be stored on a separate machine too.
  ii. SQL Server: 25% slower than InProc. Used when data is to be serialized and stored in SQL Server database.