1. A first apparatus comprising: means for receiving, from a web server, first data from a first HTTP response generated by the web server in response to a first HTTP GET request for a first URL generated by a web browser in a second apparatus; and means for causing the web browser to receive a second HTTP response that differs from the first HTTP response in that the second HTTP response contains data which causes the web browser to generate a second HTTP request in response to a web page received in response to the first HTTP GET request reaching a specified stage of loading in the web browser, wherein a memory and processor are included in the first apparatus.