1. A distributed system comprising one or more administration computers arranged in operation to: i) receive digital resource identifiers and words attributed to the digital resources, and to automatically arrange said digital resources into groups on the basis of said attributed words; ii) on a display, present a human user with a graphical user interface enabling modification of said groups; iii) modify said groups in accordance with user commands received via said graphical user interface; and iv) utilise said modified grouping in identifying one or more digital resources in said digital system; and v) using said digital resource in said distributed system.