The handbook's goal is to enable the reader to gain a deep understanding of past, current and future research and applications in the field of educational technology. From a research perspective the reader will gain an in-depth understanding of complex theories, strategies, concepts, and methods relating to the design, development, implementation, and evaluation of educational technologies. Because it combines both the insights of comprehensive experience in the field and the vision of its emerging directions, the handbook will be a comprehensive guide for researchers and practitioners working with educational technologies. The authors of the chapters represent state-of-the-art expertise in 15 countries.