Message Queuing Telemetry Transport - lightweight messaging protocol designed for IoT devices with limited bandwidth. Like a efficient postal service specifically designed for small, frequent messages.
Temperature sensors use MQTT to send readings to cloud platforms using minimal battery power and data.
AWS IoT Core and Azure IoT Hub provide managed MQTT endpoints for device connectivity and IoT features. Google Cloud Pub/Sub and OCI Streaming are managed messaging services; they don’t natively expose MQTT brokers, but MQTT devices commonly connect via a gateway/bridge that publishes into Pub/Sub or Streaming.