Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for collecting data regarding resource views. In one aspect, a method includes generating a tag that includes instructions that, upon execution of the instructions, cause a device to perform operations including identifying content located in at least one particular portion of a structured resource. The particular portion can be specified by the instructions. The operations may include generating resource view data that includes parameters identifying the device and at least a portion of the identified content. The operations may include sending the resource view data to a server. A request for the tag may be received. The tag may be provided in response to the request.