Systems modelling is an essential enabling technique for any systems engineering enterprise. These modelling techniques, in particular the unified modelling language (UML), have been employed widely in the world of software engineering and very successfully in systems engineering for many years. However, in recent years there has been a perceived need for a tailored version of the UML that meets the needs of today’s systems engineering professional. This book provides a pragmatic introduction to the systems engineering modelling language, the Sys ML, aimed at systems engineering practitioners at any level of ability, ranging from students to experts. The theoretical aspects and syntax of Sys ML are covered and each concept is explained through a number of example applications. The book also discusses the history of the Sys ML and shows how it has evolved over a number of years. All aspects of the language are covered and are discussed in an independent and frank manner, based on practical experience of applying the Sys ML in the real world.