CS 466/666 is an introduction to formal language and automata theory. In this course we will examine methods for defining syntax of languages and recognizing patterns: the languages can be defined using a rule-based systems called grammars and patterns can be recognized by the computations of finite state machines. Along with presenting the fundamentals of these two topics, the course will develop and investigate the relationships between language definition and pattern recognition. The text will be the third edition of Languages and Machines: An Introduction to the Theory of Computer Science.