Networks of entities (persons, locations, abstract objects) as well as relations between these entities play a crucial role in many application contexts. Mathematically speaking networks can be regarded as graphs. Network visualization – or graph drawing – helps human beings to understand their informa- tion content and detect, for example, inherent patterns. In this contribution applications from bioinformatics and IT security are presented together with their respective challenges. A special focus will be laid on the question how these challenges, such as the network dynamics, influence the choice of visual means.
