# MQTT Protocol
Status: public
Confidence: medium (0.775) (verified)
Last verified: 2026-05-30
Generation: human_only


## TL;DR

MQTT is a client-server publish/subscribe messaging protocol standardized by OASIS. It is often used when applications need topic-based message exchange with explicit delivery-service levels.

## Core Explanation

MQTT clients publish messages to topic names and subscribe using topic filters. The server, often called a broker, receives publications and routes matching messages to subscribers.

The protocol defines Quality of Service levels for message delivery: at most once, at least once, and exactly once. Those levels describe protocol delivery guarantees, not whether an application has processed a message successfully.

## Further Reading

- [MQTT Version 5.0](https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html)
- [MQTT Version 3.1.1](https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html)

## Related Articles

- [Message Queues](../message-queues.md)
- [Internet of Things (IoT)](../internet-of-things-iot.md)
- [TCP/IP Protocol Suite](../tcp-ip.md)