The rapid development of mobile communication networks and the availability of miniaturized and inexpensive sensor technology allow for the development of multifunctional mobile devices that are able to collect and communicate context information. We also currently see a clear trend towards the integration of embedded systems including sensors into ßmart" everyday things, which is also referred to as Ubiquitous Computing. The deployment of sensor technology allows for so-called context-aware applications, going far beyond of providing mobile access to information and computing resources. Context-aware applications exploit captured sensor information to adapt to the current situation of mobile users. For instance, the information offered to a user may depend on his current location, and the way how it is presented to him may depend on the speed he moves, whether he is on its own or with others, and so on.

In this paper, we characterize context-aware applications and present the vision of a digital world model as the foundation for this class of applications. Further, the paper discusses the benefits and reseach challenges associated with digital world models, which allow applications to take into account the state of the real world and react to state changes.