An alerting system for use in generating an alert in respect of usage of a device, the alerting system including a detector capable of detecting an event that is indicative of usage of the device, the alerting system being arranged to invoke a selected alert state prior to the activation of a forthcoming said event by a user, the alert state being selectable from a plurality of different alert states, wherein each of the different alert states represents a different stage of elapsed time since a previous said event, and wherein the alerting system is arranged to select an alert state in dependence on the elapsed time.