Topology in molecules inspired, seen and represented.

The way in which molecules are imagined and subsequently represented in drawings or models is a fundamental part of the chemist's activity. In this tutorial review we shall discuss these doings for molecules which contain an element of entanglement and whose structural representation on a plane requires the presence of crossing points. The review provides a personal view of finding inspiration, how to draw and understand topologically complex molecules, and the way they can be "switched". The review compares and contrasts approaches to illustration and conception of catenanes and knots and the dynamic processes taking place within them, and discusses the graphic tools used to portray them.