Book excerpt: "Neither an academic tome nor a prescriptive 'how to' guide, The Theory and Practice of Online Learning is an illuminating collection of essays by practitioners and scholars active in the complex field of distance education. Distance education has evolved significantly in its 150 years of existence. For most of this time, it was an individual pursuit defined by infrequent postal communication. But recently, three more developmental generations have emerged, supported by television and radio, teleconferencing, and computer conferencing. The early 21st century has produced a fifth generation, based on autonomous agents and intelligent, database-assisted learning, that has been referred to as Web 2.0. The second edition of "The Theory and Practice of Online Learning" features updates in each chapter, plus four new chapters on current distance education issues such as connectivism and social software innovations."--BOOK JACKET.