What is the difference between an ACT and SAT test? Why are there these two tests and what are they for?

What is the difference between an ACT and SAT test? Why are there these two tests and what are they for?
What exactly are the ACT and SAT tests? Why are they needed to take? What’s the difference between the two? Also, what schools ask to have these?

Here it goes: the SAT and ACT are both college admission tests. Most colleges require a certain score on one or the other to weed out applicants as part of the admissions process and in giving out merit-based scholarships.
The SAT is older, so it has more of a reputation—for a long time, some of the more prestigious east-coast schools would only accept the SAT or preferred it. The ACT was considered more for the Midwest. But now ALL (or almost all, I haven’t actually checked every last place, lol) colleges and universities will consider scores from either test, so it makes no difference. It’s a personal preference. (Although, granted, the ACT is still more COMMON in the Midwest, and the SAT on the east coast or west coast—where I’m from, what most people take is the ACT)
The differences between the two tests: The SAT tests a certain type of critical and analytical thinking, so many people find it harder than the ACT— to do really well on the SAT, you have to be able to think how the SAT wants you to think (take practice tests to get an idea of the types of questions). The ACT is much more straightforward, but covers a broader subject area. The SAT tests vocabulary intensively, the ACT doesn’t. The reading passages on the ACT are longer. The ACT is in four parts (English, Math, Reading, Science reasoning); the SAT has three sub-scores (critical reading, math, writing) but the test is divided into many shorter sections that alternate between the subjects. The Science reasoning on the ACT doesn’t test your actual science knowledge as much as it tests your ability to look at charts and graphs and scientific information they give you and interpret that. The written essay on the ACT is still optional, but whether you need to take it with the ACT or not depends on what colleges you are applying to.
My advice: take both. Most people do better at one or the other, so take both to see where you stand and send your better scores. To find out what scores you need for a certain college and whether a place actually prefers one over the other, check out their website or use’s college search.