Code: The Hidden Language of Computer Hardware and Software by Charles Petzold is a detailed, accessible exploration of how computers work at their most fundamental level. Petzold starts with simple concepts like Morse code and basic electrical circuits, gradually building up to binary code, logic gates, and the intricate workings of computer processors. Through clear explanations and engaging examples, he demystifies the layers of technology that underpin modern computing, offering readers an insightful journey from simple switches to the complex architectures that drive hardware and software. Ideal for both beginners and tech enthusiasts, the book reveals the foundational "language" that makes computers possible.