A method of operating an intermediary computer to track data requested by a user from a source server over a network, wherein the source server is arranged to communicate with the intermediary computer via a first network communications link, and the intermediary computer is arranged to communicate with the user via a second network communications link, the method comprising the computer-implemented steps of: receiving, at the intermediary computer, the requested data from the source server; and supplying, via the second network communications link, the requested data from the intermediary computer to the user; characterised in that the method comprises the intermediary computer performing the steps of: determining whether the requested data includes rights data that indicates an owner of rights to the requested data; and if the requested data includes the rights data: (a) determining whether the source server is associated with the owner of rights to the requested data; and (b) if the source server is not associated with the owner of rights to the requested data, then the intermediary computer not allowing the requested data to be supplied to the user; and (c) if the source server is associated with the owner of rights to the requested data, then the intermediary computer supplying the requested data to the user and recording that the requested data was supplied. receiving, at the intermediary computer, the requested data from the source server; and supplying, via the second network communications link, the requested data from the intermediary computer to the user; characterised in that the method comprises the intermediary computer performing the steps of: determining whether the requested data includes rights data that indicates an owner of rights to the requested data; and if the requested data includes the rights data: (a) determining whether the source server is associated with the owner of rights to the requested data; and (b) if the source server is not associated with the owner of rights to the requested data, then the intermediary computer not allowing the requested data to be supplied to the user; and (c) if the source server is associated with the owner of rights to the requested data, then the intermediary computer supplying the requested data to the user and recording that the requested data was supplied. determining whether the requested data includes rights data that indicates an owner of rights to the requested data; and if the requested data includes the rights data: (a) determining whether the source server is associated with the owner of rights to the requested data; and (b) if the source server is not associated with the owner of rights to the requested data, then the intermediary computer not allowing the requested data to be supplied to the user; and (c) if the source server is associated with the owner of rights to the requested data, then the intermediary computer supplying the requested data to the user and recording that the requested data was supplied. (a) determining whether the source server is associated with the owner of rights to the requested data; and (b) if the source server is not associated with the owner of rights to the requested data, then the intermediary computer not allowing the requested data to be supplied to the user; and (c) if the source server is associated with the owner of rights to the requested data, then the intermediary computer supplying the requested data to the user and recording that the requested data was supplied.