The addons record your travels, deaths, level-ups, catches and more while you play. The uploader is a small app that sends it here, where it joins everyone else's on the map, and your own characters get a page of their own.
You need the core, plus the modules for what you'd like to record.
WoWGeek, WoWGeek_Stats...) sits in your game's Interface/AddOns folder./reload; that's when the uploader can pick it up.First time opening it on Windows? The Mac app is signed and notarized by Apple, but the Windows version isn't code-signed yet, so Windows may be cautious. If you see "Windows protected your PC", choose More info → Run anyway.
Wondering what's shared? See About the data.