Answer:   The Global.asax file contains code for responding to application-level events raised by ASP.NET or by HttpModules. It is located in the root directory of an ASP.NET application. This file contains code that is executed in response to application-level and session-level events raised by ASP.NET or by HTTP modules.

The following are some of the important events in the Global.asax file:

Application_Init : The Application_Init event is fired when an application initializes the first time.

Application_Start : The Application_Start event is fired the first time when an application starts.

Application_AuthorizeRequest: Fired when the security module has verified that a user can access resources.

Application_ResolveRequestCache : Fired on successful completion of an authorization request.

Application_Disposed: Fired just before an application is destroyed. This is the ideal location for cleaning up previously used resources.

Session_Start : The Session_Start event is fired the first time when a user’s session is started. This typically contains for session initialization logic code.

Application_BeginRequest: The Application_BeginRequest event is fired each time a new request comes in

Application_EndRequest : The last event fired for an application request.

Application_AuthenticateRequest : The Application_AuthenticateRequest event indicates that a request is ready to be authenticated. If you are using Forms Authentication, this event can be used to check for the user's roles and rights.

Application_Error : The Application_Error event is fired when an unhandled error occurs within the application.

Session_End : The Session_End Event is fired whenever a single user Session ends or times out.

Application_End : The Application_End event is last event of its kind that is fired when the application ends or times out. It typically contains application cleanup logic.