The theory of computation is used to address challenges arising in many computer science areas such as artificial intelligence, language processors, compiler writing, information and coding systems, programming language design, computer architecture and more. To grasp topics concerning this theory readers need to familiarize themselves with its computational and language models, based on concepts of discrete mathematics including sets, relations, functions, graphs and logic. This handbook introduces with rigor the important concepts of this kind and uses them to cover the most important mathematical models for languages and computation, such as various classical as well as modern automata and grammars. It explains their use in such crucially significant topics of computation theory as computability, decidability, and computational complexity. The authors pay special attention to the implementation of all these mathematical concepts and models and explains clearly how to encode them in computational practice. All computer programs are written in C#.