I don't work anywhere near geospatial stuff, but this would have been helpful to me a few years ago when I did some hackathon projects that involved Google Maps

I don't work anywhere near geospatial stuff, but this would have been helpful to me a few years ago when I did some hackathon projects that involved Google Maps, frantically trying to integrate a number of different data sources that used coordinate systems I'd never heard of. It's worth having at least a vague awareness of this stuff if you might ever touch anything map-related.