The Prentice Hall Essence of Computing Series provides a concise, practical and uniform introduction to the core components of an undergraduate computer science degree. Acknowledging the recent changes within Higher Education, this approach uses a variety of pedagogical tools - case studies, worked examples and self-test questions, to underpin the students learning. The Essence of Databases offers a text for those students with no prior knowledge of the subject. In simple, straightforward terms the book describes the basic concepts which underpin the technology of database systems. The main areas covered are database design, relational systems, object oriented systems, distributed systems and the internal management and control of database systems. There is also a chapter on "traditional" database models (heirarchic and network). The section on database design provides a detailed summary of semantic data modelling concepts and examines how they are implemented in commonly used methodologies such as ER modelling, Functional Data Modelling and Semantic Object Modelling. The design principles outlined in this chapter are later applied in greater detail in the later sections on relational and object orientated systems, making an explicit link between the theory and practice of database technology. The section on internal management demonstrates how logical database structures are stored in physical devices and considers the related problems of concurrent access control and database transaction integrity. There is a closing chapter on distributed systems which focuses mainly on the complexities of internal management that they create.