This is a Map Key/Legend for the World Map.

*WARNING* No longer accurate for those on the public beta branch, maybe not even for the non beta release but I'm not going to backdate to find out so leave a complaint if you want me to remove this guide

Composited from the wiki and fixed errors.
I couldnt find an image just like this so hopefully this makes it to Googles No. 1 Search result when you search for a key.