MQTT stands for Message Queue Telemetry Transport. It is an extremely lightweight messaging protocol based on the publish/subscribe model and favored for use with constrained devices, low bandwidth, or where the network is unreliable.
MQTT was developed by Dr. Andy Stanford Clark of IBM and Arlen Nipper of Arcom (now Eurotech) in 1999. It was designed with the purpose of minimizing the device's resource requirements and network bandwidth consumption, very high scalability, smaller code footprint, and also ensuring the delivery of messages/signals. These attributes of the MQTT protocol make it the right candidate for Internet of Things use cases where we have massive numbers of constrained devices with limited memory, network bandwidth, ...
