I hate to be "that guy", but in their enthusiasm I think the writers forgot to account for the "what is this?" demographic. I know what OSM is. I understand tha

I hate to be "that guy", but in their enthusiasm I think the writers forgot to account for the "what is this?" demographic. I know what OSM is. I understand that Google Maps tracks me to no end. I'm curious what exactly this is in a nutshell, and it would be good for one of the early paragraphs. It looks like a UI on top of OSM, but this wouldn't be the first. I assume there's something else special here. I appreciate any work in this area. I like the idea of a self-hosted map, if indeed this is open source to that extent.