Programming Microsoft® ASP.NET 3.5

Conclusion

HTTP handlers and HTTP modules are the building blocks of the ASP.NET platform. ASP.NET includes several predefined handlers and HTTP modules, but developers can write handlers and modules of their own to perform a variety of tasks. HTTP handlers, in particular, are faster than ordinary Web pages and can be used in all circumstances in which you don't need state maintenance and postback events. To generate images dynamically on the server, for example, an HTTP handler is more efficient than a page.

Everything that occurs under the hood of the ASP.NET runtime environment occurs because of HTTP handlers. When you invoke a Web page or an ASP.NET Web service method, an appropriate HTTP handler gets into the game and serves your request. ...