Middleware exists because IoT systems are heterogeneous. A broker that lets a Modbus gateway, a LoRaWAN server and a mobile app exchange messages without direct connections is middleware; so is a layer that converts every vendor’s payload into one data model, or a message queue that buffers bursts. Many IoT platforms are, at heart, packaged middleware with management features on top.
The benefit is interoperability and loose coupling: you can replace a device type or an analytics tool without rewriting everything else. The cost is another moving part that must be sized, secured and understood, and middleware that grows into a bespoke platform can be harder to maintain than the problem it solved.
Part of the IoT Glossary. Spotted an error or a missing term? Tell us.