This book is an outcome of the lectures delivered by the author for engineering students at Kyushu University, Japan, Korea Advanced Institute of Science and Technology, South Korea, and Ryerson University, Canada. The text started when the author was at Kyushu University, Japan. The author has been doing research on the subject of sensors and actuators for aerospace systems for the last fifteen years. During the course of research and teaching this subject, the author realized that there is an earnest need of a text which may provide basic understanding of inherent complexity in modelling avionics systems. This text fulfils this goal through a step by step approach that explains each concept in a simple way with mathematical details and simple notations. This textbook is written for engineers and students pursuing study or research on the dynamics and control of aircraft or space systems. The author has used all contents of this textbook in a core course on Avionics and Systems (one semester, four hours a week). This text assumes that the reader is well acquainted with elementary calculus and linear algebra. Enough care has been taken so that the reader may attempt different types of problems. Each concept has been discussed with sufficient mathematical background supported by examples. A complete set of problems has been added to the end of every chapter. This textbook provides the practical aspects of designing aerospace systems with a focus on sensors and actuators. In writing this textbook, I have tried my best to provide the best relevant materials on the subject. I encourage and welcome all comments and suggestions to make this book more relevant to the contents of your course or research study. Please address your comments to kdkumar@ryerson.ca.