A method and apparatus are disclosed for providing information about a real-world space such as an exhibition space. In a preferred embodiment, users visiting a space are equipped with mobile devices in communication with a service system. The mobile devices are arranged to deposit virtual markers with the service system as the users progress around the space. These markers are stored and decayed with time, either individually or in location-dependent marker aggregations, and data on the current strength values of the markers or marker aggregations is used to provide information concerning use of the space.