Distributed systems are a continuously expanding area of computer science and computer engineering. This book addresses the need for literature on modeling and simulation techniques for distributed systems. For simulation modeling of distributed systems in the book, a specific class of extended Petri nets is used that allows to easily represent the fundamental processes of any distributed system. The book is intended, first of all, as a text for related graduate-level university courses on distributed systems in computer science and computer engineering. Other computer science and computer engineering courses would also find the book useful as a source of practical information for a broad community of those graduate students who are busy with simulation in their study and research. The book can be useful also to academics who give related graduate courses or deliver research-oriented modules for graduate students. Further, the book can be helpful to system architects and developers who apply modeling and simulation techniques as a step in the design and implementation of their systems. Containing a large number of models, with commented source texts and simulation results, it can also serve as valuable reference book for researchers who want to develop their own models in terms of Petri nets.