 Dynamic Epistemic Logic is the study of a family of modal logics, each of which is obtained from a given logical language by adding one or more modal operators that describe model-transforming actions. If \([A]\) is such a modality, then new formulas of the form \([A]F\) are used to express the statement that F is true after the occurrence of action A. To determine whether \([A]F\) is true at a pointed Kripke model \((M,w)\) (see  Appendix A  for definitions), we transform the current Kripke model M according to the prescription of action A and we obtain a new pointed Kripke model \((M',w')\) at which we then investigate whether F is true. If it is true there, then we say that original formula \([A]F\) is true in our starting situation \((M,w)\). If F is not true in the newly produced situation \((M',w')\), then we conclude the opposite: \([A]F\) is not true in our starting situation \((M,w)\). In this way, we obtain the meaning of \([A]F\) not by the analysis of what obtains in a single Kripke model but by the analysis of what obtains as a result of a specific modality-specified Kripke model transformation. This is a shift from a static semantics of truth that takes place in an individual Kripke model to a dynamic semantics of truth that takes place across modality-specified Kripke model transformations. The advantage of the dynamic perspective is that we can analyze the epistemic and doxastic consequences of actions such as public and private announcements without having to “hard wire” the results into the model from the start. Furthermore, we may look at the consequences of different sequences of actions simply by changing the sequence of action-describing modalities. 