Operating System is an insightful work that elaborates on fundamentals as well as advanced topics of the discipline. It offers an in-depth coverage of concepts, design and functions of an operating system irrespective of the hardware used. With neat illustrations and examples and presentation of difficult concepts in the simplest form, the aim is to make the subject crystal clear to the students, and the book extremely student-friendly. The book caters to undergraduate students of WBUT, who would find the conceptual discussions highly informative and enriching. Tailored as a guide for self-paced learning the book equips budding system programmers with the right knowledge and expertise.