This book contains comprehensive theory and solved practice questions for following topics : Computer Science, Pedagogy, fundamentals of computers, Data Processing, Programming Fundamentals, Data Structures and Algorithms, Computer Organization and Operation System, Communication and Network Concepts, Network Security, Database Mgt. System, System Analysis and Design, Internet of things and its application. Although, this book is especially written for the aspirants of Basic Computer Instructors organized by Rajasthan Staff Selection board, it is also a good read for the post of Senior computer instructors.