Exploration and play behaviour form the subject of this book, in which a wide range of research activities, both theoretical and practical, are presented from various fields. In particular, the emphasis on applications (for example, in the development of software) demonstrates the integrated approach to basic and applied research. The authors come from many different countries and represent various theoretical approaches, enabling the reader to acquire an up-to-date overview of the field and thus form an opinion of his/her own regarding this field of research.