Systems biology is a rather new field, which has gained a lot of attention recently and which most likely is here to stay. The core objective is to understand and study living systems as systems, which cannot completely be understood by studying its parts in separation. This has two important consequences. First, the data is typically collected using high-throughput technologies, ideally collecting large amounts of in vivo data of parallel processes in various normal and perturbed states, with a high time-resolution and in absolute numbers. Second, because of the large amount and complexity of the gathered data, and because of the complexity of underlying explanations, mathematical modelling is typically involved in the data interpretation. Systems biology is therefore a child of for instance the following fields: theoretical biology, complexity theory, bioinformatics, physiology, and of course classical experimental fields such as cell biology and biochemistry.