Think of a fog computing node as a physical server that resides between the edge devices (thermostats, robots, in-vehicle computers) and the back-end systems, typically hosted on public clouds. The fog nodes respond to an architectural problem: too much latency to pass requests all the way back to the public cloud-based services and not enough horsepower to process the data in the edge device itself.
This three-tier system adds another compute platform that is able to do some—if not most—of the back-end processing. This addresses the concern that cheaper edge devices with lower power don’t have the processing and storage power to deal with the incoming data natively.
