Interesting Puzzle

[ihardlyknowher]

Forgive me if this has been posted or if it is trivially easy. I found it interesting.

Your are given 12 marbles, identical in appearance. Exactly one marble has a mass either slightly more OR slightly less than the other 11 (the difference is so minimal no human could possibly detect it without the use of scientific equipment). You are given a balance and allowed to use it exactly 3 times. You must determine which marble has a slightly different mass and whether it has more or less mass than the other 11. How do you do it?