The textbook "Conceptual Modeling - ER 2008" offers a comprehensive analysis and discussion on conceptual modeling, which is recognized as a crucial tool for software development in information systems and data processing. It addresses the various languages, methods, and tools needed to understand and represent application domains. The book is the result of the International Conference on Conceptual Modeling, which serves as a leading forum for current research and applications in this field. The topics covered range from theories about concepts and ontologies to methods for developing and communicating conceptual models. The 33 research papers published in this volume were selected by a large program committee and provide valuable insights into the latest developments and techniques in the area of conceptual modeling.