Dynamic epistemic logic is the logic of knowledge change. This is not about one logical system, but about an entire family of logic that allows us to determine aspects of static and dynamic multi-agent systems. 'Epistemic logic' is a picture of multi-agent epistemic logic - the logic of knowledge - including capital for the group of operators, such as general knowledge and general. 'Public Announcement' is a detailed and comprehensive introduction to the dynamic logic operator knowledge to the public announcement was added. 'Epistemic Actions' introduces a generalization of public announcement logic to more complex epistemic actions. 'Completeness' gives details of the proof of completeness for the logic introduced in the 'epistemic logic', 'Public Announcements' and 'Action Models'.