MQTT (Message Queue Telemetry Transport) is a message protocol that is based on a publish/subscribe model, in which publishers send messages to a MQTT server which forwards messages to multiple subscribers avoiding point-to-point connections. The protocol is extremely lightweight and supported by many IoT applications across many industries.

The characteristics of MQTT are that the protocol is designed for:

• Low Resource devices,
• in low-bandwidth networks and high latency
• based on subscribe / publish model
• widely used in the IoT service development
• consisting of an MQTT Broker and MQTT Clients

Reference: MQTT.org