The book collects and condenses the experience of years of teaching compiler courses and doing research on formal language theory, on compiler and language design, and to a lesser extent on natural language processing. In the turmoil of information technology developments, the subject of the book has kept the same fundamental principles over half a century, and its relevance for theory and practice is as important as in the early days.

This state of affairs of a topic, which is central to computer science and is based on consolidated principles, might lead us to believe that the accompanying textbooks are by now consolidated, much as the classical books on mathematics. In fact this is rather not true: there exist fine books on the mathematical aspects of language and automata theory, but the best books on translators are sort of encyclopaedias of algorithms, design methods, and practical know-how used in compiler design. Indeed a compiler is a microcosm, featuring a variety of aspects ranging from algorithmic wisdom to CPU and memory exploitation. As a consequence the textbooks have grown in size, and compete with respect to their coverage of the last developments on programming languages, processor architectures and clever mappings from the former to the latter.