"A course on operating system is an essential part of any computer science education. An operating system is a system software which manages computer hardware and interacts with the users. This book deals with all the major concepts of Operating Systems with relevant practical explanations. It will be easier for even a non-computer science student to understand the concepts. This book is written for the introductory course on operating system at the junior and the senior undergraduate level or at the first year graduate level. The fundamental concepts and algorithms covered in the book are often based on those used in the existing commercial operating systems. The aim is to present these concepts and algorithms in a general setting that is not tied to one particular operating system, and present it in the simplest and easiest way to the readers. With a lot of examples that pertain to the most popular operating systems, it also includes Linux (Ubuntu 12.10 Quantal Quetzal and windows 8.1 machines)."