ASP.NET provides a low-level request/response API that enables developers to use .NET Framework classes to service incoming HTTP requests. Developers accomplish this by authoring classes that support the System.Web.IHTTPHandler interface and implement the ProcessRequest() method and the IsReusabl() method.

Handlers are often useful when the services provided by the high-level page framework abstraction are not required for processing the HTTP request. Common uses of handlers include filters and CGI-like applications, especially those that return binary data.