The SAT and the ACT are standardized tests, and most colleges and universities require at least one as part of the admissions process. The SAT is a 3-hour-and 45-minute test that consists of three 800-point portions: Critical Reading, Math, & Writing. The ACT last 3 hours and 25 minutes, and is comprised of four sections: English, Mathematics, Reading, and Science Reasoning. Deciding which test to take used to depend on the location of the school a student was applying to, but today, nearly all colleges accept both tests.

This article from Math.com explores the differences between the two tests more thoroughly, as does this breakdown from The Princeton Review. This article from Peterson's may help you decide which test is best suited to you, and you can check out SAT/ACT optional schools here. Additionally, in this post from The New York Times, SAT and ACT officials answer readers' questions about the standardized tests.