This book is designed for an introductory course on Operating System and related matters. This volume provides basic operating system concept with easy understanding for learners. It is written after understanding what students need. During the lecture session students face some challenges with respect to basic learning the concepts along with application. This book explains the practical concept and how to execute general and meticulous practical features. A good number of solved practical oriented examples with explanations are given. All chapters are based on the core concept of operating system and are being illustrated focusing undergraduate and postgraduate students.