This book forms the mathematical and logical foundation of modern computer science and plays a vital role in the design of intelligent and efficient computing systems. In today's era of AI, compiler construction, cyber security, ML, data science, and advanced software engineering, understanding formal languages, automata, and computational complexity has become increasingly important in day-to-day life. The concepts of automata and computation theory are widely applied in algorithm design, programming language development, pattern recognition, NLP, and system optimization. This book provides a comprehensive and systematic introduction to the fundamental concepts of computation. It begins with finite automata, regular expressions, and regular grammars, enabling readers to understand the basics of pattern recognition and language processing. It further explores context-free grammars and pushdown automata, which are essential for syntax analysis and compiler design. Advanced topics such as Turing machines, recursive and recursively enumerable languages, undecidability, Chomsky hierarchy, linear bounded automata, and computational complexity are discussed in a simple and structured manner.