Computer systems application refers to the utilization of software and hardware components to perform various tasks and activities such as data processing, communication, entertainment, and business operations. This textbook covers the fundamental concepts of computer systems and their applications in various fields. It provides an in-depth understanding of computer architecture, operating systems, networking, and database management systems. With its practical approach, Computer Systems Application equips readers with the knowledge and skills needed to design, develop, and implement computer-based systems. It serves as a valuable resource for students of Computer Science, software engineering, and related fields, as well as professionals in the technology industry who wish to enhance their knowledge and skills. This book introduces the readers to the basic concept of Computer Science. It sheds light on the background of computers, computer programs, languages, data communication, and computer network. In addition, this book also emphasizes the role of virtual reality, Artificial Intelligence, and IoT.