Most colleges require you to take a test before they'll admit you as a student. Four-year colleges and universities generally require the ACT or SAT. Two-year colleges may require the ACT or other placement test. Trade schools may require the ACT or some other placement test.
The SAT has three sections: critical reading, math and writing. The SAT Subject Test consists of one-hour tests in specific subjects. The SAT also has an essay section. Check with the school you plan to attend to see if any are required. For more information or to register online, visit www.collegeboard.org.
The ACT has sections on English, math, reading and science reasoning, plus an optional writing test. For more information, visit www.act.org/.
The best way to prepare for the ACT and SAT is to take challenging courses in high school, study and learn. There are other things you can do that'll help. You can take practice tests online, or you can buy practice tests for use at home. Some high schools and colleges offer ACT/SAT prep classes for free or a small fee. Familiarize yourself with the sections and directions.