I define serendipity as the art of making an unsought finding. And I propose an overview of my collection of serendipities, the largest yet assembled, chiefly in science and technology, but also in art, by giving a list of ‘serendipity patterns’. Although my list of ‘patterns’ is just a list and not a classification, it serves to introduce a new and possibly stimulating perspective on the old subject of serendipity. Knowledge of these ‘serendipity patterns’ might help in expecting also the (...) unexpected and in finding also the unsought. * I acknowledge A. D. de Groot, R. C. M. Noordam, B. P. van Heusden, T. Pinkster, C. J. van den Berg, T. A. F. Kuipers, A. Wegener Sleeswijk and my referee for their suggestions and I dedicate this article to T. A. van Kooten. Cases and studies of serendipidy are welcome. À propos: a travelling serendipity exhibition is available, also for ‘new democracies’: ‘Freedom of opportunity as developed by democracy is the best human reaction to divergent phenomena. We may, in fact, define ‘freedom’ as ‘the opportunity to profit from the unexpected.’ (Langmuir [1956]). (shrink)