MQTT: What is the protocol?

Why MQTT (Message Queuing Telemetry Transport) is relevant for businesses

Modern businesses face the growing challenge of connecting an increasing number of devices and systems. Especially in the field of IoT, fast, reliable, and lightweight communication channels are essential. Traditional protocols like HTTP often reach their limits in these scenarios, and that’s exactly where the MQTT protocol comes into play, offering an efficient solution for machine-to-machine data transmission. It is lightweight, flexible, and specifically designed for unstable networks. But what is Message Queuing Telemetry Transport exactly, and why is it becoming increasingly important? This article dives deeper into the meaning of MQTT and why using this IoT protocol can be a smart move for modern companies.

What is MQTT (Message Queuing Telemetry Transport)? Definition & meaning

The abbreviation MQTT stands for Message Queuing Telemetry Transport and was developed by IBM in 1999. The goal was to create a network protocol specifically suited for devices with limited resources that could function reliably even in unstable or low-availability network environments. Today, MQTT is an open standard maintained by OASIS and is considered a proven solution for many IoT applications. The MQTT protocol is widely used in industries such as manufacturing, building automation, and mobility – anywhere that requires fast and secure communication between many devices. Some typical characteristics of Message Queuing Telemetry Transport include:

• Lightweight design with minimal overhead
• Reliable communication even with low bandwidth or high latency
• Flexible scalability through a clear MQTT topic structure

These features make the messaging protocol especially attractive for modern, connected systems like smart homes, industrial machines, or sensor networks. Without focusing on specific use cases, it's easy to see why the combination of efficiency, stability, and simplicity has made MQTT a leading IoT protocol. 

MQTT vs. TCP

TCP is a transport protocol that ensures reliable, connection-oriented data transmission between endpoints. MQTT, on the other hand, is a messaging protocol built on top of TCP, offering features like the publish-subscribe model, message queues, and retained messages. While TCP provides the foundation for dependable data transfer, the messaging protocol enhances communication for IoT applications — especially in environments with limited bandwidth and resources.

MQTT vs. HTTP

HTTP is a widely used web protocol based on a synchronous request-response model, ideal for traditional client-server communication. MQTT on the other hand uses a lightweight, asynchronous publish-subscribe model optimized for real-time data exchange. Compared to HTTP, MQTT has lower overheads, uses less bandwidth, and is better suited for IoT applications with many devices and frequent data updates.

Structure and functions of the MQTT protocol

The functionality of Message Queuing Telemetry Transport follows a clear process based on the publish/subscribe principle. Communication does not happen directly between devices but is coordinated through a central MQTT broker. This component handles the distribution of all messages. A typical workflow looks like this:

1. Establishing a connection
   An MQTT client (e.g., a sensor or a controller) connects to the MQTT broker, while authenticating itself (e.g., via username and password). The connection is established using the TCP protocol, which ensures reliable and error-free data transmission. The TCP standard is part of both the TCP/IP model and the OSI model.
2. Subscribing to topics
   A client that wants to receive data subscribes to one or more MQTT topics. A topic functions like a thematic address, for example: “warehouse/temperature”.
3. Publishing messages
   Another client, the publisher, sends data to that specific topic, which is then delivered to the broker.
4. Distributing the message
   The MQTT broker then automatically forwards the message to all clients (the subscribers) that have subscribed to the relevant topic.
5. Choosing the Quality of Service (QoS)
   Both publishers and subscribers can define a Quality of Service level:

• QoS 0: The message is sent once, with no confirmation.
• QoS 1: The message is delivered at least once, with acknowledgment.
• QoS 2: The message is delivered exactly once, using a more secure two-step process.

Additionally, extra features can be used to optimize communication within the MQTT network. One of these is the so-called Retained Message, where the broker stores the most recently published message of a specific topic. When a new subscriber joins this topic, they immediately receive the latest data without having to wait for the next publication. 

Another useful feature is the Last Will and Testament (LWT). With this, a client can compose a message that the broker will automatically send to a defined topic if the client unexpectedly loses the connection. This allows for reliable communication of sudden outages and better tracking of system behavior.

This entire process ensures stable, flexible, and resource-efficient communication – even in unstable network environments.

Choosing and implementing the MQTT broker

The central hub of any MQTT infrastructure is the broker. It receives messages from clients and distributes them precisely to those that have subscribed to the relevant Message Queuing Telemetry Transport topic. Without the broker, the protocol simply wouldn't work.

There are various options available when choosing a broker: open source solutions (ideal for smaller projects), powerful commercial variants (with support and high scalability) or cloud services, where operations are completely outsourced. Key factors in the decision-making process include scalability, security (e.g., TLS encryption, access control, authentication), and ease of integration into existing systems. Implementing an MQTT broker typically follows a straightforward process:

1. Set up the broker: Install it locally or deploy it in the cloud.
2. Configure the MQTT client: Establish the connection to the broker and set authentication credentials.
3. Structure the topics: Organize them logically, such as “production/machine/temperature”.
4. Test the connection: Send and receive initial messages to verify functionality.
5. Implement security measures: Enable TLS, set up authentication, and manage access rights.

Following these steps enables organizations to integrate the MQTT protocol into their infrastructure in a reliable, scalable, and secure way.

Security aspects when using MQTT

When working with the MQTT protocol, security is a key consideration, especially in production-level IoT environments. Since Message Queuing Telemetry Transport does not provide encryption by default, specific protective measures are essential to ensure safe operation. 

Secure communication starts with authentication, ideally using a username and password or, even better, digital certificates. Additionally, the entire data transmission should be encrypted using TLS/SSL to protect messages from unauthorized access. This ensures message integrity and confidentiality, even across insecure networks. 

Proper configuration of the MQTT broker is equally important. Access rights must be strictly assigned so that each MQTT client can only read or write to the MQTT topics that are relevant to its function. Open ports and insecure default settings must be avoided at all costs. Continuous monitoring of the MQTT server helps detect suspicious activity early. Log analysis, regular updates, and well-defined security policies complete the picture – making Message Queuing Telemetry Transport a secure choice for connected systems.

MQTT for businesses: Examples explained

The protocol is used across a wide range of industries and is especially well-suited for applications where devices need to send data on a regular basis. Here are some common examples of how Message Queuing Telemetry Transport is applied in practice:

Logistics
The protocol enables real-time monitoring of supply chains as sensors can track conditions such as temperature, location, or vibrations. The data is then sent immediately to an MQTT server and processed, which allows for better management and supervision of the transportation processes.

Energy Management
MQTT supports the collection of consumption data. Devices like electricity meters, heat pumps, or solar panels regularly transmit status updates. These messages are centrally analyzed and used to optimize energy usage.

Automotive Industry
Connected vehicles send diagnostic data or location information to central systems. Fleet operators can then use this data to schedule maintenance or adjust routes immediately.

Smart Cities
Message Queuing Telemetry Transport manages a wide range of sensors and systems – from street lighting and air quality monitoring to waste management. All communication is handled through MQTT clients that interact with an MQTT broker.

A major advantage of Message Queuing Telemetry Transport is that it can be integrated into existing IT structures, allowing companies to gradually expand their systems. It acts as an interface, connecting old and new technologies. Whether for remote monitoring, automation, or data collection – by using the MQTT IoT protocol, companies can make their processes more transparent and efficient.

 

Why Message Queuing Telemetry Transport outperforms other protocols

In modern, connected systems, devices often need to communicate under challenging conditions, such as weak network coverage, limited power supply, or minimal processing capacity. The MQTT protocol was specifically developed to meet these demands. It is lightweight, efficient, and reliable, even in high-latency or unstable networks, and compared to traditional protocols like HTTP, AMQP, or CoAP, it offers several key advantages.

While HTTP operates on a request-response model and typically transfers large amounts of data with each interaction, MQTT uses a streamlined push model where devices only send data when new information is available — eliminating the need for constant polling. Compared to CoAP, which is based on the connectionless UDP protocol, Message Queuing Telemetry Transport is more reliable and stable due to its use of TCP. When measured against AMQP, it stands out for its simplicity and lower system requirements. Here’s a clear comparison of MQTT, HTTP, CoAP, and AMQP:

In relation to its minimal overhead, targeted message delivery, and robust transport, MQTT is ideal for resource-constrained devices like sensors, actuators, and battery-powered systems. That’s why Message Queuing Telemetry Transport is not just an IoT protocol – it's often the first choice for digital transformation across a wide range of industries.

MQTT as a key technology in IoT

The IoT protocol MQTT has established itself as a lightweight, efficient, and highly flexible communication tool. It is perfectly tailored to the requirements of interconnected systems in the age of the Internet of Things. It enables reliable data transmission with minimal resource consumption and can be easily integrated into existing infrastructures. As a result, companies benefit from stable communication, low data usage, and a high level of scalability. 

With the development of MQTT 5.0, even more possibilities open up: In combination with technologies such as Artificial Intelligence and Big Data, it becomes the key technology for intelligent and future-proof systems worldwide. Those who rely on Message Queuing Telemetry Transport today are laying the foundation for the connected solutions of tomorrow.

Frequently asked questions about MQTT

What is the meaning of MQTT?
MQTT stands for Message Queuing Telemetry Transport. It is a lightweight messaging protocol designed for efficient communication between machines (M2M), especially in environments with limited bandwidth, high latency, or unreliable networks. Originally developed by IBM in 1999, the protocol has become a global standard for IoT communication.

How does MQTT work?
Message Queuing Telemetry Transport is a simple messaging protocol that uses a publish/subscribe model. Devices using MQTT are called clients, and they do not communicate directly with each other. Instead, they send and receive messages through a central server called a broker. A device that sends data is called a publisher, and it sends the data to a specific topic. The broker receives the message and forwards it to all clients that have subscribed to that topic. It uses TCP to send messages, which helps make sure the messages are delivered reliably, and also allows the setting of a Quality of Service (QoS) level to control how messages are delivered: just once, at least once, or exactly once.

 

How do I set up an MQTT broker and client?
Setting up the Message Queuing Telemetry Transport involves a few clear steps:

1. Install an MQTT broker – You can choose open-source options or commercial/cloud solutions.
2. Configure the broker – Define access rights, enable TLS encryption, and set up authentication.
3. Connect an MQTT client – Use a device or software tool to establish a connection with the broker, typically over TCP using credentials.
4. Create MQTT topics – Organize messages with structured topics like factory/machine/status.
5. Test the connection – Send and receive sample messages to verify functionality and stability.

What is the role of MQTT in IoT (Internet of Things)?
The protocol is one of the most widely used IoT protocols. It enables seamless and energy-efficient data exchange between sensors, machines, applications, and cloud platforms. Its lightweight design makes it ideal for battery-powered and resource-constrained devices and, thanks to its flexibility and scalability, MQTT supports real-time monitoring, automation, and remote control across various industries, forming the backbone of many smart systems.

How can I secure communication using MQTT?
Since Message Queuing Telemetry Transport doesn’t provide encryption by default, specific security measures are essential. The first step is to encrypt all data transmissions using TLS/SSL to protect messages from third-party access. In addition, every MQTT client should be authenticated through secure methods such as usernames and passwords or digital certificates. It’s also critical to define strict access permissions, so each client can only interact with the MQTT topics relevant to its function. Open ports and unsafe default settings should be disabled. A strong monitoring setup rounds out the security strategy and helps detect unauthorized access or system failures early.

How is MQTT different from HTTP, and why is it often the better choice?
The main difference between MQTT and HTTP lies in the communication model. While HTTP relies on a classic request/response structure, MQTT uses a more efficient publish/subscribe approach. This means devices only send data when there’s something new to report, eliminating the need for constant polling. As a result, data traffic is significantly reduced. The Message Queuing Telemetry Transport is also much more resource-friendly, due to its minimal overhead and persistent TCP connection.

What are some common use cases for MQTT?
The protocol is commonly used across many industries due to its lightweight design and efficient communication model. In logistics, it supports real-time tracking of temperature, location, and shipment conditions. In the energy sector, Message Queuing Telemetry Transport helps monitor smart meters, solar panels, and heating systems by sending regular updates for analysis and optimization. The automotive industry uses MQTT to transmit diagnostics and location data from vehicles to cloud platforms, enabling better fleet management. In smart cities, it connects systems like street lighting, air quality sensors, and waste management for streamlined urban operations. Industrial automation also benefits from MQTT, as it enables real-time data exchange between machines, sensors, and control systems to improve efficiency and maintenance planning.