They countdown until they fire a rocket. 10, 9, ... , 3, 2, 1, we have lift off. Well, you can count down to just about anything. Usually when you are close to the important date you start a countdown. Right now, we are counting down to the Rugby World Cup, which starts in about 3 months.

counting down meaning is like 10,9,8,7,6

counting down means that, by number, the number is going down like: 5,4,3,2,1. Counting up is, going by number, the number is going up like: 1,2,3,4,5.