1. A computer-implemented method for attributing activity to a user, comprising the steps of: sending from a first content provider in response to a first request for content from a user browser executing on a user device, requested content and a first identification (ID) to the user browser, the first ID capable of being stored on the user device; receiving a second request for content at a second content provider from the user browser, the second request including user identification information, the second content provider: retrieving attributes associated with the user identification information from an attribute server; generating a temporary ID; sending the attributes and the temporary ID to an analytics server; sending a response to the user browser, the response including the temporary ID and an instruction to provide a user profile server with the first ID and the temporary ID; receiving a user profile associated with the first ID and the temporary ID from the user profile server at the analytics server; and using the temporary ID to associate the attributes with the user profile at the analytics server.