The era of computer revolution began almost 50 years ago and since then, the developments in the fi eld have been very rapid. Every sphere of human activity has been affected by developments. An essential part of every computer is the operating system, which provides a platform for the proper usage of computer resources during the operation of a computer. Therefore, we believe that operating systems must be understood by everyone who uses a computer. Operating Systems is an insightful work elaborating on the fundamentals as well as advanced topics in the discipline. Keeping the needs of the students in mind, this work offers an in-depth coverage of concepts, design and functions of an operating system irrespective of the hardware that will house it. With neat illustrations, examples and presentation of diffi cult concepts in the simplest form, the USP of this book lies in it being extremely student-friendly. Based upon the updated university curriculum, this book caters to BTech Computer Science and Engineering (IV semester) students, who would fi nd the introductory and advanced discussions highly informative and enriching. Operating Systems is a great guide for self-paced learning and will go a long way in equipping budding system programmers with the right knowledge and expertise. Text Layout The text is organised into 12 chapters. • Chapter 1 introduces operating system, its services and structure. Also, it provides an insight into the organization of computer system. • Chapter 2 deals essentially with the basic concepts of processes such as process scheduling, operations on processes and communication between processes. • Chapter 3 helps to understand the need and advantages of threads, various multithreading models as well as threading issues. • Chapter 4 spells out the scheduling criteria and different types of scheduling algorithms. It also discusses several issues regarding scheduling in multiprocessor and real-time systems. • Chapter 5 throws light on several methods used for achieving synchronization among cooperating processes. • Chapter 6 describes the deadlock situation and the conditions that lead to it. It also provides methods for handling deadlocks.