Bisimulation is an instance of coinduction. Both bisimulation and coinduction are today widely used, in many areas of Computer Science, as well as outside Computer Science. Over, roughly, the last 25 years, enhancements of the principles and methods related to bisimulation and coinduction (i.e., techniques to make proofs shorter and simpler) have become a research topic on its own. In the paper the origins and the developments of the topic are reviewed.