The book Theory of Automata and Formal Languages' contains the syllabi of the Theory of Automata and Formal Languages of Computer Science Engineering, Information Technology and MCA streams of various Universities. This book is also good for students doing C-Level from DOEACC. This book provides an introduction of Finite Automata, Regular Expressions, Context Free Grammars, Push Down Automata, Turing Machines and other concepts in this course. Students taking a course in Theory of Automata and Formal Languages get benefited in a variety of ways. They may need it to study other subjects, in research, or in their careers. They may also use the concepts and techniques learned here to broaden their knowledge of computing. In this book, basic concepts are explained in as lucid manner as possible.