Answer:   Application Events: Application_Start , Application_End, Application_AcquireRequestState, Application_AuthenticateRequest, Application_AuthorizeRequest, Application_BeginRequest, Application_Disposed, Application_EndRequest, Application_Error, Application_PostRequestHandlerExecute, Application_PreRequestHandlerExecute,Application_PreSendRequestContent, Application_PreSendRequestHeaders, Application_ReleaseRequestState, Application_ResolveRequestCache, Application_UpdateRequestCache
Session Events: Session_Start,Session_End

Answer:   Following are the event handlers that we can have in Global.asax file:-

Application_BeginRequest() – fired when a request for the web application comes in.

Application_AuthenticateRequest –fired just before the user credentials are authenticated. You can specify your own authentication logic over here.

Application_AuthorizeRequest() – fired on successful authentication of user’s credentials. You can use this method to give authorization rights to user.

Application_ResolveRequestCache() – fired on successful completion of an authorization request.

Application_AcquireRequestState() – fired just before the session state is retrieved for the current request.

Application_PreRequestHandlerExecute() - fired before the page framework begins before executing an event handler to handle the request.

Application_PostRequestHandlerExecute() – fired after HTTP handler has executed the request.

Application_ReleaseRequestState() – fired before current state data kept in the session collection is serialized.

Application_UpdateRequestCache() – fired before information is added to output cache of the page.

Application_EndRequest() – fired at the end of each request

Application_Start() – fired when the first resource is requested from the web server and the web application starts.

Session_Start() – fired when session starts on each new user requesting a page.

Application_Error() – fired when an error occurs.

Session_End() – fired when the session of a user ends.

Application_End() – fired when the web application ends.

Application_Disposed() - fired when the web application is destroyed.