To understand the fundamentals of computer science it is essential for us to begin with study of the related mathematical topics ranging from discrete mathematics, concepts of automata theory and formal languages. It is high time to recognize the importance of discrete mathematics as it finds various applications in the field of computer science. However, it requires a full fledged study and its potential with respect to computer sciences and natural sciences have long been well recognized. To understand the principles of computer science that is evenly acknowledged as mathematical foundation of computer science, this book present a selection of topics both from discrete mathematics and from automata theory and formal languages. The objective of selection of topics was due to my aspiration to commence with most of the fundamental terminology employed in higher courses in computer science as plausible. As per the requirements of the study, the formal appearance of the discrete mathematics includes set theory, algebraic systems, combinatorics, Boolean algebra, propositional logic, and other relevant issues. Likewise, abstract models of computations, models of computability, language theory concepts, and the application of language theory ideas are the subject matter of the concepts of automata and formal languages. These topics will also assist to understand the concepts and philosophies used in advanced stages of computer learning such as computation theory and computability, artificial intelligence, switching theory and logic design, design of softwares like high speed compilers, sophisticated text processors and programming languages, assembly and rescue of information.