One you've been on the site and participated enough to get "shares" and appreciation for comments etc, your hubwheel next to your name in the upper left corner begins to populate. Once it's made a full rotation you get some increased abilities on the site:
1. You get a badge to give. +!
2. You get the ability to add community tags to posts. +#
Check out the FAQ page, I believe it's mentioned there. Hope this helps!