A system for implementing in a networked client-server environment an anonymous and user-transparent technique for uniquely identifying network-distributed devices, comprising: a client device having a browser; a content server connected via a global communication network to the client device; wherein the content server is configured to receive a request from the client device browser for a content page and to transmit to the client device a file for the content page, the file including an embedded code for downloading and executing a script on the client device browser; a unique device identification management system in communication with the client device via the global communication network, the unique device identification management system including a database and being configured to: receive from the client device unique device identification data; select a globally unique identifier for association with the client device; and save the globally unique identifier in the database of the unique device identification management system; and the unique device identification management system includes a unique device profile management system and a device capabilities database system, wherein: the device capabilities database system is configured to append select device capabilities to an incoming Internet address URL received from the device browser of the client device and to redirect the request for a content page to the unique device profile management system characterised in that, the file includes an embedded code for downloading and executing a script on the client device browser; the system also includes a script server connected to the client device via the global communication network; wherein the script server includes executable instructions for transmitting the script to the client device, wherein the script, once instantiated and started, transparently inserts unique device identification requests into the content page, for subsequent execution by the device browser; the unique device identification data received from the client device does not comprise a browser-side cookie; and the unique device profile management system is configured to retrieve device profiles existing in a profile database of the unique device profile management system for comparison with a profile of the client device and to sequentially eliminate profiles not matching until a single profile is left or all profiles have been eliminated. receive from the client device unique device identification data; select a globally unique identifier for association with the client device; and save the globally unique identifier in the database of the unique device identification management system; and the device capabilities database system is configured to append select device capabilities to an incoming Internet address URL received from the device browser of the client device and to redirect the request for a content page to the unique device profile management system characterised in that, the file includes an embedded code for downloading and executing a script on the client device browser; the system also includes a script server connected to the client device via the global communication network; wherein the script server includes executable instructions for transmitting the script to the client device, wherein the script, once instantiated and started, transparently inserts unique device identification requests into the content page, for subsequent execution by the device browser; the unique device identification data received from the client device does not comprise a browser-side cookie; and the unique device profile management system is configured to retrieve device profiles existing in a profile database of the unique device profile management system for comparison with a profile of the client device and to sequentially eliminate profiles not matching until a single profile is left or all profiles have been eliminated.