If it's worth saying, but not worth its own post, even in Discussion, it goes here.
It's your karma for the past 30 days. (It should say this if you hover your mouse pointer over it, which doesn't help if you don't have a mouse pointer.) It's not computed in real time so it's sometimes out of sync with your total karma.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.