The field of electrets has developed rapidly with an increasing number of new materials, methods for investigating charge-storage phenomena, and the development of creative and exciting applications. This third edition of Electrets, printed in two volumes, documents the significant contributions to the knowledge and understanding of the field. Vol. 1: Reprint of the 1987 second edition with updates and corrections. This volume covers all the basics plus the important research from 1920 to 1987. Vol. 2: Six chapters on the hot topics in electrets providing a digest of the significant progress in electret research over the 11 years since the 1987 publication of the second edition. This compendium is based on special issues of the IEEE Transactions on Dielectrics and Electrical Insulation, with further extensive updates by each contributor. Although there have been monographs and proceedings of conferences published on this topic, there had been no cohesive treatment of the entire field of electrets until the original publication of Dr. Sessler's seminal work, Electrets, first edition. Now he and his colleagues, plus younger colleagues who bring a fresh perspective, continue to contribute and update the series by offering this latest comprehensive survey of noteworthy developments in the field of electrets.