The Internet of Things (IoT) connects billions of physical devices—sensors, actuators, gateways, and edge computers—to the internet, enabling real-time data exchange, automation, and intelligence at scale. Born from embedded systems and machine-to-machine communication, IoT now spans consumer, industrial, healthcare, and smart city domains. In 2026, Edge AI, 5G connectivity, and mature security standards are reshaping the ecosystem from cloud-centric to distributed, locally-intelligent architectures. Understanding IoT means mastering not just device hardware, but communication protocols, data pipelines, power optimization, and security from chip to cloud—where every design choice trades off latency, bandwidth, energy, and cost.