Most introductory books on cyber security are either too technical for popular readers, or too casual for professional ones. This book, in contrast, is intended to reside somewhere in the middle. That is, while concepts are explained in a friendly manner for any educated adult, the book also necessarily includes network diagrams with the obligatory references to clouds, servers, and packets. But don’t let this scare you. Anyone with an ounce of determination can get through every page of this book, and will come out better informed, not only on cyber security, but also on computing, networking, and software. While it is true that college students will find the material particularly accessible, any adult with the desire to learn will find this book part of an exciting new journey. A great irony is that the dizzying assortment of articles, posts, and books currently available on cyber security makes it difficult to navigate the topic. Furthermore, with so much information coming from writers with questionable backgrounds in cyber security, separating the wheat from the chaff has become an almost impossible task for most readers, experienced or otherwise. This book is written specifically to address that problem. That is, we set out to create an accessible but technically accurate work on cyber security that would not insult the intelligence of our readers. We avoid the temptation to navigate away from the technical issues, choosing instead to steer toward the detailed concepts in the hopes that our readers will develop new understanding and insights. The material here provides a technical grounding that is commensurate with what you might receive in a college course on the topic. If you are an engineer, developer, or student, then you are certainly in the right place. On the other hand, if you work in management, executive leadership, or some other non-technical role, then this is exactly the technical grounding in cyber that you’ve been looking for. Anyone who has not been sleeping in a cave the past few years knows the consequences of misguided decision-making in cyber security. Business leaders colliding with this complex issue will find their intellectual property gone and their services blocked by hackers. Government and political leaders who misstep in this area will find their careers, programs, and campaigns ruined. Consider this: Target, Home Depot, and Sony have seen massive attacks on their infrastructure, and most citizens, including our leaders, have no idea how or why this occurred. Similarly, we watched data leaks from the US Office of Personnel Management and the Democratic National Committee, and most people have only a vague sense of how such cyber attacks were accomplished. Perhaps more disturbingly, decision-makers in our society have no idea how to reduce this risk. Because they typically have zero technical understanding, they are forced to suggest simple, trite measures they can understand like awareness, penalties, and compliance. Our approach here is to demonstrate that cyber security attacks are best avoided through improved technology and architecture. Written from the perspective of the professional cyber security executive, long-time academic, and industry analyst (Edward Amoroso), and the graduate computer science student, software developer, and occasional hacker (Matthew Amoroso), this book provides a concise technical introduction to cyber security that keeps things as straightforward as possible, but without veering into silly analogies. If you successfully complete this book, you will no longer have to shrug when asked about cyber security. Rather, you will be able to lean in and offer an informed opinion based on an introductory grounding in the fundamental aspects of cyber security technology. Our goal is to expand your understanding and make you a more informed and educated adult.