For over half a century, an increasing number of satellites have fragmented in orbit, creating a large amount of hazardous orbital debris which threaten the safety of useful functioning satellites and space missions. This book discusses the theory behind these fragmentations followed by studies of actual cases.The book begins with a survey of satellite fragmentations in orbit and the consequent formation of orbital debris in chronological order. Next, the fundamental physical processes underlying satellite fragmentations are outlined and the methods of analyzing satellite fragmentations presented. The rest of the book presents analyses of the major satellite fragmentation events including accidental and intentional breakups, those due to explosions and collisions, as well as those belonging to the unknown category.