Petri Nets are graphical and mathematical tool used in many different science domains. Their characteristic features are the intuitive graphical modelling language and advanced formal analysis method. The concurrence of performed actions is the natural phenomenon due to which Petri Nets are perceived as mathematical tool for modelling concurrent systems. The nets whose model was extended with the time model can be applied in modelling real-time systems. Petri Nets were developed originally by Carl Adam Petri, and were the subject of his dissertation in 1962. Since then, Petri Nets and their concepts have been extended and developed, and applied in a variety of areas: office automation, work-flows, flexible manufacturing, programming languages, protocols and networks, hardware structures, real-time systems, performance evaluation, operations research, embedded systems, defence systems, telecommunications, Internet, e-commerce and trading, railway networks, biological systems. Like industry standards such as UML activity diagrams, Business Process Model and Notation and EPCs, Petri nets offer a graphical notation for stepwise processes that include choice, iteration, and concurrent execution. This book focuses on Petri Nets applications in two main areas: manufacturing and computer science. These two areas have still huge influence on our lives and our world. The theory of Petri Nets is still developing. Although many other models of concurrent and distributed systems have been developed since the introduction in 1964 Petri nets are still an essential model for concurrent systems with respect to both the theory and the applications.