What is the purpose of global.asax in asp.net

Question

How can we use global.asax in asp.net? And what is that?

Answer 1

The Global.asax file, also known as the ASP.NET application file, is an optional file that contains code for responding to application-level and session-level events raised by ASP.NET or by HTTP modules.

http://msdn.microsoft.com/en-us/library/2027ewzw.aspx