MQTT (Message Queue Telemetry Transport) is an open network protocol specifically designed for communication between devices with limited resources and unstable network connections. Originally designed in 1999 for industrial communication, MQTT was developed to collect data from remote sensors with limited connectivity. Since 2013, MQTT has been established as the standard for the Internet of Things.

MQTT uses a client-server structure and is an integral part of the Internet of Things (IoT), playing an important role in networking devices and providing real-time data transfer. Thanks to its flexibility, efficiency and scalability, MQTT is used in a wide range of applications, including increasingly in smart home systems.

In smart home systems, MQTT is used to integrate sensors and actuators, among other things. The MQTT server, also known as the MQTT broker, controls the data traffic, while the integration interface acts in the form of an MQTT client.

In many smart home devices, the MQTT client is present in addition to the actual main system. MQTT uses the usual network standard using specially defined ports. Data transmission can be unencrypted or encrypted.