In the US we've got a few different testing standards. The SAT and ACT are pretty common. But they're a secondary part of normal high school classes. Basically, we're all required to do twelve years of schooling, grades 1-12. And in grade 11 or 12 you take the SATs or the ACTs, or whatever other standard your part of the country adheres to. You get a score for the SAT/ACT (I think the SAT is 0000/1600 possible points, and the ACT is 00/25 possible points). You also get letter grades for your classes, like math, english, history, whatever.

Colleges and Universities in the States look at your grades in High school (Grades 8-12, and really, only grades 11-12 seem to count if you have a decent score on your SAT/ACT). Then they look at your SAT/ACT scores. Then they look at your extracurricular activities, such as sports, student government, volunteer time, wacky science inventions, that might speak to your credit. And usually you write a letter explaining why you want to go to such and such school and they consider that as well.

Then, apparently, they throw all that stuff in the garbage and sacrifice a chicken. They look at the chickens guys and decide whether or not you should be admitted into their college/university.

And that's how we do it in the States.