IoT protocols explained simply
The Internet of Things has long since entered our daily lives, even if we often don’t notice it. Environmental sensors, smart meters, industrial devices, smart homes: all these objects communicate with each other and with central systems thanks to protocols specifically designed to be lightweight, reliable, and suitable for contexts very different from those of the traditional web.
However, when people start talking about IoT protocols, the risk is getting lost among acronyms and overly academic definitions. MQTT, CoAP, ZigBee, LoRaWAN may sound similar, but in reality they address very different needs.
MQTT: the king of lightweight messaging
MQTT is probably the most well-known and widely used IoT protocol. It was created for scenarios where devices have limited resources, unstable connections, and need to exchange small messages reliably. Its operation is based on a publish/subscribe model: devices publish messages on specific “topics,” and other devices or applications subscribe to those topics to receive them.
From a technical standpoint, MQTT runs over TCP and uses a central broker that manages all communications. This approach greatly simplifies the architecture and allows it to scale easily, even with thousands or millions of devices. The different Quality of Service levels make it possible to choose how much reliability is needed, balancing traffic and delivery security. This is why MQTT is widely used in industrial environments, cloud IoT, and integrations with backend platforms.
CoAP: the web adapted to objects
CoAP, an acronym for Constrained Application Protocol, was created with a clear idea: bringing the logic of the REST web into the IoT world. The main operations closely resemble HTTP, with GET, POST, PUT, and DELETE requests, but everything is optimized to work on devices with limited memory and processing power.
Unlike MQTT, CoAP relies on UDP instead of TCP, reducing overhead and latency. This makes it suitable for local networks and scenarios where communication is direct between devices, without a central broker. From a security standpoint, CoAP uses DTLS, a variant of TLS designed for UDP. It is a very common choice in home automation, building automation, and sensor networks where a more “peer-to-peer” approach is needed.
ZigBee: the protocol that lives in the network
ZigBee is not just an application protocol, but a complete stack that also covers the lower layers of communication. It is designed for short-range mesh networks, in which each device can forward messages from others, increasing reliability and coverage without the need for high power.
In practical terms, ZigBee is widely used in smart homes and building automation. Light bulbs, motion sensors, thermostats, and smart plugs often communicate using this standard. The mesh network is its real strength, because it allows devices to stay connected even if one node is turned off or fails, reducing dependence on a single central point.
LoRaWAN: little data, very long distances
LoRaWAN comes into play when the main issue is not speed, but distance. This protocol is designed for very long-range communications, even over several kilometers, with extremely low energy consumption. It is ideal for battery-powered sensors that need to last for years and send only a small amount of data per day.
From an architectural point of view, LoRaWAN uses a network of gateways that collect messages from devices and forward them to a central network server. Bandwidth is very limited and transmissions are short, but this is an acceptable trade-off in scenarios such as smart cities, precision agriculture, environmental monitoring, and distributed infrastructures. Here the priority is covering large areas at low cost, not exchanging large amounts of data.
How to choose the right protocol
There is no single best IoT protocol overall, only the one most suited to the context. MQTT is perfect when cloud integration and centralized message management are required. CoAP works well in lightweight local networks with REST logic. ZigBee is ideal for short-range domestic and mesh networks. LoRaWAN becomes unbeatable when distances are large and devices need to consume very little power.
Understanding these differences helps not only in choosing the right technology, but also in designing IoT systems that are more efficient, scalable, and sustainable over time. And it is precisely here that protocols, often taken for granted, really make the difference.
