MQTT (Message Queuing Telemetry Transport) is a lightweight publish-subscribe messaging protocol ideal for IoT applications, designed for efficient communication in low-bandwidth or unreliable networks. It operates on a scalable model where devices publish or subscribe to topics, ensuring organized data flow and minimizing network overhead. MQTT's architecture includes brokers for message forwarding, and it supports various use cases such as smart home automation, industrial IoT, and environmental monitoring, with options for custom and cloud-based broker solutions.