Kind of. It stands for American College Testing, so it sounds like it's some big exam that decides your future, it's only a big deal if you fail hard or win hard, and even then, you can retake it as many times as you want between Junior year and graduation, and the highest score is the one that's taken into account.
My brother says that apparently, a 27, along with my GPA, is scholarship level, and gives me openings to schools all across the country, so that's kinda nice.