ASP.NET Application and Session state variablesBy default, ASP.NET maintains page data between the requests using mechanism called View state. Every web form has view state property to retain data. The form's view state can retain data only in that form. So, when you need one form data in other form, you can't rely on view state. ASP.NET provides state variables in the Application or Session objects that helps in maintaining state of the form which can be accessed in other form.
Application state variables
The data stored in these variables is available to all the users i.e. all the active sessions.
Session state variables
These are available to the single session who has created the variables.
Point to be noted about Application and Session state variables
These variable can store any type of data.
Maintaining Session state affects performance.
Session state can be turned off at the application and page levels.
Application state variables are available throughout the current process, but not across processes.