What is IoT? Explained simply
IoT is everywhere—but what does that actually mean?
What do your smart thermostat, an ESP32 prototype, a Bluetooth-enabled electric toothbrush, and a connected truck have in common?
They all belong to the “Internet of Things” – IoT for short.
The term is used everywhere, but rarely explained.
This article provides you with clear and practical information on:
What exactly is IoT?
How it works technically
Where you already use IoT in everyday life (and in industry)
Which devices are included
And why the topic is not only cool, but also critical
What does IoT mean – explained simply
IoT stands for “Internet of Things.”, also: Internet der Dinge.
This refers to a network of physical devices, which:
Collect data (e.g., via sensor)
communicate with each other or with a cloud
react, control, or automate
Example: A temperature sensor regularly sends measurements to your ESP32. This controls a relay—or sends the data via MQTT to your smart home server.
The key point:
IoT devices are not traditional computers, but they behave like small, networked mini PCs – often invisible, but active.
What are typical IoT devices? (Examples)
| IoT device | Function |
|---|---|
| smart thermostat | Measure temperature, controllable via app |
| water meter | Send consumption data via radio or Wi-Fi |
| ESP32 + Sensor | Collect & send measurement data |
| voice assistant | Central control (via cloud) |
| truck tracker | Transmit GPS position live |
| Smart lamp | Can be switched via app or voice command |
| washing machine | Error diagnosis or consumption report |
Depending on the application, the devices can be connected via Wi-Fi, Bluetooth, Zigbee, LoRa, NB-IoT, or cellular networks.
How does IoT work technically?
IoT usually consists of three layers:
1. Sensors / Actuators
Temperature, light, movement, air quality, voltage...
Actuators such as relays, motors, LEDs, valves
2. Communication
Protocols: MQTT, HTTP/REST, CoAP, Zigbee, Modbus
Transmission: Wi-Fi, Ethernet, 5G, LoRaWAN, Bluetooth
Example: An ESP32 sends measured values to a local Mosquitto broker via MQTT. Home Assistant reads this data and uses it to control the lighting.
3. Data processing / Cloud / Server
Data is evaluated, stored, or visualized.
e.g. with Node-RED, Home Assistant, Grafana, or in the cloud
IoT in everyday life – where you already use it
IoT is no longer a thing of the future, but rather standard:
Smart home devices (heating, windows, lighting)
Wearables (fitness trackers, smartwatches)
Agriculture (soil moisture, weather data, feeding)
Industry (predictive maintenance, machine control)
Automotive (OTA updates, telematics, sensor fusion)
And IoT is often invisibly integrated – e.g. in washing machines, electricity meters, or medical devices.
DIY IoT with ESP32, Arduino, and more
Many makers use IoT for their own projects—for example:
Indoor air quality monitor with ESP32 + BME280 + MQTT
Smart garden irrigation system
Energy consumption logger with Open Energy Monitor
Home Assistant integration via REST or MQTT
Popular tools/platforms:
ESPHome
Tasmota
PlatformIO
Node-RED
Mosquitto
OpenHAB / Home Assistant
Criticism of the IoT – justified or panic?
As exciting as IoT is, there are also serious problems:
Security:
default passwords
Open ports
No updates
OTA without signature
Gateway for attacks (e.g., botnets such as Mirai)
Cloud dependency:
Many devices only work with the Internet.
Manufacturers can retroactively disable devices
Data protection often lacks transparency
Tip: Use local IoT solutions whenever possible—e.g., Home Assistant + MQTT—instead of cloud-based solutions.
What is the difference between IoT and smart home?
| IoT | Smart Home | |
|---|---|---|
| Definition | All kinds of networked devices | Focus: Home automation |
| site | everywhere (industry, mobility, cities, etc.) | at home |
| devices | Sensors, actuators, machines, vehicles | Lamps, thermostats, cameras, voice assistants |
| Goal | Efficiency, automation, networking | Comfort, control, energy savings |
Smart Home is a sub-area of IoT.
FAQ – Frequently asked questions
What does IoT mean in German?
IoT stands for Internet of Things, auf Deutsch: Internet der Dinge.
What are typical IoT devices?
Example: Smart thermostat, ESP32 with sensors, smart light bulb, GPS tracker, voice assistant, electricity meter.
Is IoT dangerous?
It can be unsafe when manufacturers build poor software. Updates, secure networks, local control, and no open ports are important.
What is MQTT in the context of IoT?
MQTT is a lightweight protocol, ideal for IoT. Devices publish or subscribe to messages via a broker.
What platforms are available for DIY IoT?
Popular options include: Home Assistant, ESPHome, Node-RED, Tasmota, PlatformIO, Mosquitto.
Conclusion: IoT is everywhere—and it is becoming increasingly important
Whether in industry, everyday life, or the maker world, IoT has long since permeated our devices, homes, and systems.
If you understand IoT, you understand today's technology.
And best of all: With tools such as ESP32, MQTT, VSCode, and others, you can build it yourself—securely, locally, and without cloud dependency.