A brief history of process algebra

This note addresses the history of process algebra as an area of research in concurrency theory, the theory of parallel and distributed systems in computer science. Origins are traced back to the early seventies of the twentieth century, and developments since that time are sketched. The author gives his personal views on these matters. He also considers the present situation, and states some challenges for the future. Note: Also report CS-R 04-02, Department of Mathematics and Computer Science, Technische Universiteit Eindhoven, http://www.win.tue.nl/fm/pubbaeten.html.