A display system for use in displaying data in respect of usage of a device, the display system including: a detection system capable of detecting events that are indicative of usage of the device; and a display arranged to display data, the display system being arranged to invoke a selected display mode on the display, and being adapted, in response to detection of a given said event, to invoke a selected display mode, the display mode being selectable by the display system from a set of a plurality of different display modes in dependence on an elapsed time between a previous said event and said given event, each of the different display modes identifying a different stage of elapsed time.