ASP.NET Tutorial : Asynchronous Pages in ASP.NET 4.5
To make a page asynchronous in earlier versions of ASP.NET, the page has to implement the interface IHttpAsyncHandler and define concrete definitions to all the methods declared in the interface. This takes considerable amount of time and effort to make the page asynchronous. In ASP.NET 4.5, we can turn the execution of any operation asynchronous[…]