Abstract
<jats:p>The world around us is becoming smarter every day. Your smartwatch counts your steps. Your refrigerator knows when you are running low on milk. Street lights switch off at dawn without anyone touching a switch. Traffic signals adapt in real time to ease your commute. These everyday marvels share a single common backbone: the Internet of Things — IoT.</jats:p> <jats:p>When I first began teaching IoT to engineering undergraduates, I discovered a persistent gap in available learning materials. Most books assumed prior programming experience or access to expensive hardware. Others buried students in theory without ever having them build anything real. A third category provided project instructions without explaining the principles underlying them, leaving students unable to adapt what they had built to new situations. This book was written to close that gap.</jats:p> <jats:p>IoT Unplugged is a hands-on guide for complete beginners — students, hobbyists, and technically curious professionals who want to understand, build, and deploy connected systems. It uses two of the most accessible and powerful tools available: the Arduino microcontroller platform for interacting with the physical world, and the Python programming language for building the software infrastructure that connects devices to the internet and to each other.</jats:p> <jats:p>The thread that runs through every chapter of this book is APIs — Application Programming Interfaces. APIs are the invisible highways of the connected world. They are how your Arduino sensor sends a temperature reading to a cloud server, how your phone retrieves that reading, and how a dashboard visualises it as a live chart. Understanding APIs is the single most transferable skill in modern IoT development, and it is the skill this book is designed to build from the ground up.</jats:p> <jats:p>You will not need a computer science degree to read this book. You will need curiosity, patience, and a willingness to connect a few wires and type a few lines of code. Every concept is introduced from first principles. Every code example is fully annotated. Every project is buildable with hardware that costs less than a meal at a restaurant.</jats:p> <jats:p>By the final chapter, you will have built a complete, working IoT system: a physical sensor node that reads temperature and humidity, an ESP32 that transmits the data over WiFi to a Flask REST API, an MQTT broker routing real-time messages to subscribers, and a live Plotly Dash web dashboard displaying the data with charts and alerts — all secured against unauthorised access. More importantly, you will understand every component of that system well enough to extend it, modify it, and apply its principles to problems of your own choosing.</jats:p> <jats:p>Welcome to the Internet of Things. Let us build something remarkable together.</jats:p>