Open access book published by Springer with associated Mathematica software. PRÉCIS: This book introduces the basic principles of control theory in a concise self-study tutorial. The chapters build the foundation of control systems design based on feedback, robustness, tradeoffs, and optimization. The approach focuses on how to think clearly about control and why the key principles are important. Each principle is illustrated with examples and graphics developed by software coded in Wolfram Mathematica. All of the software is freely available for download. The software provides the starting point for further exploration of the concepts and for development of new theoretical studies and applications. NOTE: I wrote this tutorial because I could not find a simple, brief introduction to the foundational concepts of control theory. I needed to understand those key concepts before I could read the standard introductory texts on control or read the more advanced literature. Ultimately, I wanted to develop sufficient understanding so that I could develop my own line of research on control in biological systems.