I dont really know what this is, or where to put it. but my rank was above 2000 3 days ago... then 2 days ago i was in the 500s. so i was like, wow thats awsome. and then yesturday my rank was 26... yeah i know. guess what. today my rank is almost 6000. why? and, what determines the rank

Rank is based off of the rank you are in your current belt.

but.... but..... i am i was brown belt now and when i became 26......

Every belt has its own rank board. The person closest to getting their next belt is ranked 1 on the list.

You got 2000, then 500, then 26, because you were nearing your next belt. You're 6000 now because you just started your new belt, your ranking isn't as low because you're further away from achieving your next belt than most others on the same belt are.

your the 26th best brown belt worldwide

As I explained, its a different ranking board per belt. The ranks are based off of qi.

So it would go like this;

Black belt:
1. Player 1 : qi 1999
2. Player 2 : qi 1991
3. Player 3 : qi 1985
4. Player 4 : qi 1962
5. Player 5 : qi 1955
... etc etc,

Black Belt 2nd Dan:
1. Player 6 : qi 1996
2. Player 7 : qi 1992
3. Player 8 : qi 1987
4. Player 9 : qi 1977
5. Player 10 : qi 1969

thanks dude! i get it!

You're both correct, as far as I know the rank is based of Qi per belt as Diealready said and your win ratio. It's more effected by how close you are to reaching your next belt though.