Theory of Computing (ToC) is dedicated to the foundational, theoretical study of computation: What is a computer? What is computation and where does it manifest? What are the capabilities and limitations of different kinds of computers? The method we use to study this question is the mathematical method: we use precise mathematical definitions to model various systems where computation (or a computation-like phenomenon) occurs, and then we use rigorous, deductive reasoning (i.e., mathematical proofs) to understand the behavior and properties of such systems.
