Apache ZooKeeper Essentials is intended for students, software professionals, and administrators who are involved in the design, implementation, or maintenance of complex distributed applications and platforms. This book will allow both beginners as well as individuals who already have some exposure to ZooKeeper to master the concepts of ZooKeeper, its usage, and programming. Some sections of this book assume that the readers have prior knowledge of the concepts of distributed systems and are familiar with a high-level programming language, but no prior experience with ZooKeeper is required.