A method for associating a device with a user including the action of receiving from a first computerized device operated by a first user a first data-content including a plurality of first data items, including clickstream data. An action of setting rules for computing scores representing similarity between a first data item received from the first computerized device and a second data item received from a second computerized device. An action of collecting the plurality of the first data items and the second data items, from the plurality of computerized devices of the plurality of computerized devices. An action of computing the score representing similarity between at least one pair of computerized devices respectively providing the first and the second data items. And an action of determining that the pair of computerized devices are operated by a same user if the score reaches a predetermine value.