Global.asa has several purposes, but its essential use is to provide a place where you can handle events that are global in nature. These events are the Application and Session on start and on end events, and give you a place to run code that can initialize and clean up variables and objects that are used by the rest of your asp pages. In other words, Global.asa is for things that are NOT at the Request level of your application. Your typical ASP pages deal with the request and response objects, and the Global.asa does not.
A typical example is to use Global.asa to keep track of the number of users on line by setting up a counter application variable in the Application_OnStart method, incrementing it on each Session_OnStart method, and decrementing it on each Session_OnEnd.
Woody Z http://www.learntoprogramnow.com