One of the most important recent developments in software engineering is the Unified Modelling Language (UML) standard for documenting software designs. Written by UML's inventors (the so-called Three Amigos of software engineering), The Unified Modelling Language User Guide provides a very appealing guide to all the fundamentals of using UML effectively. The book opens with a basic tour of the essential concepts and modelling diagrams used in UML, including class diagrams, use case diagrams and basic modelling principles. The authors pay close attention to modelling classes (and documenting the relationships between classes) as well as use case diagrams (which show how software will be used by various actors in a system). This book mixes in a little software engineering theory, too, but it makes use of clear examples and actual UML diagrams to illustrate key concepts.