A method of profiling communication traffic of users in a data network, comprising: monitoring communication traffic originated by a user of a communication terminal; and assigning to the user of the communication terminal a unique and anonymous user traffic identifier, wherein the user traffic identifier is related to a user address assigned to the communication terminal in the data network. Also, the user traffic identifier is adapted to be included in the communication traffic with respect to that user. The method further includes communicating the unique and anonymous user traffic identifier to the user terminal and having the user communication terminal include the user traffic identifier in the user traffic, upon receipt of communication traffic including the user traffic identifier, obtaining a descriptor of the received communication traffic useful to describe the detected traffic and at least temporarily storing the obtained descriptor; and building an anonymous user profile related to the user's communication activities based on the stored descriptors.