The user is able to maintain state. State is the ability to retain information. There are two main types of states: 

Application State, in which all information pertaining to an application is avaliable to all users of an application. 

Session State, in which information is available only to a user of a specific session.

The Session object is used to manage information for a user when the user is using an application. Thus, the session belongs to user. The Application object is used to store common information that can be shared between all users of a single ASP-based application. 

Using the Global.asa File 

Each ASP-based applciation can have one Global.asa file (.asa stands for Active Server Application). This file is stored in the root directory of the application. ASP reads Global.asa when 

The server receives the first post-startup request for any .asp file in a given application. That is, the first request for any ASP application forces ASP to read Global.asa file 

A user who does not have a session requests an .asp file in an application

Application-start events, session-start events, or both. 
Application-end events, session-end events, or both. 
Object tags. You can use the <OBJECT> tag in a Global.asa file.