This is a gentle introduction to so-called dynamic epistemic logics that can describe how agents change their knowledge and beliefs. We start with a concise introduction to epistemic logic, through the example of agents holding playing cards; and, mainly for the purpose of motivating the dynamics, we also briefly introduce the concepts of shared and common knowledge. We then pay ample attention to the logic of public announcements, wherein agents change their knowledge as the result of publicly perceived events. In that setting, we also present the unsuccessful updates: formulas that become false when announced. We then present more complex epistemic updates. Finally, we briefly present a framework for jointly modeling (defeasible) belief and knowledge, and belief revision.