The chapters in the Introduction present in brief themes relating to Εnvironmental Ηistory at an international level and within the framework of Byzantine Studies. Discussed next is the aim of writing this book, which is to give a synthetic conspectus of diverse subjects pertaining to Environmental History, through the material offered by epistolography. The book is structured on the basis of themes concerning aspects of land use, climate, water, and animals. It offers numerous case studies of specific places which were visited by the letter-writers, who were eye witnesses of the conditions prevailing, which means that the information in most cases is direct.