Interoperability is the ability for two or more systems to interoperate, i.e., to share and use common information and/or to use functionality of one another. The purpose of the book is to explain what one should know to be able to understand or implement systems interoperability at the technical, semantic and organization levels of an enterprise system or of a collaborative automated system. In particular, it presents the rationale, the basics, the common methods and the essential standards for the engineering of interoperable systems. The book is intended to serve as a textbook for those who need (1) to study basic principles, concepts and techniques along with applications of systems interoperability and (2) need to know applicable standards for planning, engineering or implementing interoperability solutions. Applications will concern, but are not limited to, automated (collaborative) environments. The book should also serve as a reference document for students and academia at under-graduate and graduate levels or in engineering schools as well as for researchers, practitioners, consultants and engineers faced with interoperability problems in service, industrial, government or administrative sectors.