1. A method comprising: transmitting a first content to a content provider for transmission to a content display site by the content provider, wherein the first content comprises an instruction that, when executed by the content display site, causes the content display site to request second content from a monitoring provider; receiving a request for the second content from the content display site at the monitoring provider; and in response to the request for the second content, sending the second content to the content display site, wherein the second content comprises a monitoring instruction that, when executed by the content display site, causes the content display site to monitor the first content and to transmit monitoring information related to the first content to the monitoring provider, wherein the monitoring provider is different from the content display site and the content provider, and the monitoring provider did not provide the first content to the content display site.