MQTT

MQTT (Message Queuing Telemetry Transport) is an exceptionally fast and reliable communication protocol used in smart homes for transmitting messages between devices. In simple terms, it works like a "postal system" where devices either send information (Publish) or receive it (Subscribe) without needing to connect directly to each other.

The heart of this system is a central server known as an MQTT Broker. For example, if a smart thermometer detects a temperature change, it sends this message to the Broker. The smart home hub (or smart thermostat) that needs this data immediately retrieves it from the Broker and adjusts the heating accordingly.

The huge advantage of MQTT is its low data consumption and lightning-fast response times, making it the gold standard for advanced platforms like Home Assistant or Node-RED. It also allows devices (such as Shelly Wi-Fi modules) to communicate purely locally without relying on external cloud services, drastically increasing the speed and security of your entire Smart Home.