Easy-to-read & write style. A step-by-step solution of DEA & NFA approach that is used in almost all DFA & NFA approach that is used in almost all DFA & NFA examples in chapter 03 (Finite State Machine). Every chapter is supported with multiple choice questions, theoretical questions and numerical for better practice. Due care in taken to balance the mix of notations and words in mathematical statements. The book is presented with an approach to explain the concepts in lucid style and comprehensible language. A large number of attractive and accurate figure and graphs have been drawn which enable students to grasp the subject in an easy way. Systematic and sequential arrangement of different topics. Rich pedagogy..