This is a VERY good question.
CAPRI is an experiment to see if scientists are good enough at predicting how different molecules assemble themselves into useful parts. Basically, someone in the world does expensive experiments to find out how two large biological molcules (with thousands of atoms) come together – exactly what shape they form. Then, before they let anyone know the answer, they can start a CAPRI challenge, where scientists like me try and find the answer using nothing but computers. Then, once everyone has put their predictions in, the real answer is revealed and we all get to find out who succesfully predicted it.
I’m actually doing a round of CAPRI right now, so I’m really busy.