This revised new edition containing numerous new and heavily updated chapters provides readers with the essential information needed to understand the central topics of terminology in healthcare, the understanding of which is an asset to be leveraged in care and research. Twenty-five years ago the notion that terminology should be concept-based was all but unknown in healthcare; now almost all important terminologies are at least partly concept-based. With no general model of what a terminology was or should be, there were no tools to support terminology development and maintenance. Steady progress since then has improved both terminology content and the technology and processes used to sustain that content. This new edition uses real world examples from the health sector to delineate the principal issues and solutions for the field of data representation. It includes a history of terminologies and in particular their use in healthcare, including inter-enterprise clinical andresearch data aggregation. Terminology, Ontology and their Implementations covers the basis, authoring and use of ontologies and reference terminologies including the formalisms needed to use them safely. The editor and his team of carefully chosen contributors exhaustively reviews the field of concept-based indexing and provides readers with an understanding of natural language processing and its application to health terminologies. The book discusses terminology services and the architecture for terminological servers and consequently serves as the basis for study for all students of health informatics.