Luciano Floridi presents a book that will set the agenda for the philosophy of information. PI is the philosophical field concerned with (1) the critical investigation of the conceptual nature and basic principles of information, including its dynamics, utilisation, and sciences, and (2) the elaboration and application of information-theoretic and computational methodologies to philosophical problems. This book lays down, for the first time, the conceptualfoundations for this new area of research. Floridi describes what the philosophy of information is; helps the reader to gain a better grasp of the complex and multifarious nature of the various concepts and phenomena related to information; and answers several key theoretical questions of greatphilosophical interest, arising from the investigation of semantic information.