ACTs and SATs are standardized tests given to students. Both tests are for college admission; most schools do not prefer one over the other. Not every college requires these, so be sure to check. For example, most community colleges require the Accuplacer, not an ACT/SAT.
The tests cover mathematics, reading, English, and science. On the SAT, you can earn up to 1600 points; college admissions don’t accept anything below a score of 400. You can score up to 36 points in the ACT; for college admissions, you must score at the very least an 18. The average time it takes to take the ACTs is 2 hours and 55 minutes while the SATs last for 3 hours.
You can sign up for these tests online. Go to https://collegereadiness.colle... for the SATs or https://www.act.org/content/ac... to sign up for the ACTs.