What could I use a global.asax file for?

[Smurfsdabomb]

I'm doing a college project and I'm trying to demonstrate a wide use of the tools available. Simply put what does a global.asax do and what is a simple demonstration I could do using it?

Thanks!

 

[JohnH]

Start with these:
Global.asax Syntax
Understanding the Global.asax file: ASP Alliance
Global.asax - Wikipedia, the free encyclopedia
.NET - Exploring the Global.asax file in ASP.NET