1. A method for providing an overview of a plurality of contexts of a target environment, the method comprising: receiving event data representing a plurality of events in the plurality of contexts over a monitoring period; displaying a schematic representation of the event data over the monitoring period using only a portion of the event data, the schematic representation being indicative of an activity density of the event data over the monitoring period; and displaying, together with the schematic representation, a detailed graphical representation of the event data over a specified portion of the monitoring period using the event data for the specified portion of the monitoring period.