Operating systems are one of the most important inventions after the internet. They refer to the system software that manages the program and hardware components of the computers. The most common and famous operating systems are Unix, Microsoft Windows, etc. This book outlines the processes and applications of operating systems in detail. It picks up individual branches and explains their need and contribution in the context of the growth of the subject. Some of the diverse topics covered in this text address the varied branches that fall under this category. This textbook is a complete source of knowledge on the present status of this important field. It will serve as a reference to a broad spectrum of readers.