I have never used handlers (.ashx) files in any of my .NET web development projects, but this all changed in the last two days. The way I understand a handler is that it acts as a ‘process’ handler and does not write any output to the browser. Where would you use this? Well I used it for a shopping cart (but in hindsight I will change this) by using a handler to process the items added to the cart. The handler took a querystring and created a datatable of none existed or added the data to a datatable if that datatable already existed and stored the datatable in a session variable, which could then be accessed throughout the application. Accessing querystring variables in a handler file requires that you implement the IHTTPHandler interface, i.e. you cannot simply type Request.Querystring in the handler.