The focus of this book is on finite problems and concrete computational models. It covers the traditional topics of formal languages, automata and complexity classes, as well as an introduction to the more modern topics of space-time tradeoffs, memory hierarchies, parallel computation, the VLSI model, and circuit complexity. These topics are integrated throughout the book as illustrated by the early introduction of P-complete and NP-complete problems. Models of Computation provides the first textbook treatment of space-time tradeoffs and memory hierarchies. It gives a comprehensive introduction to computational complexity as well as a brief but modern coverage of circuit complexity. Parallelism is integrated throughout the book.