Many of the tests required and used by colleges to admit students in the USA are administered by an organization called ETS (Educational Testing Services). Some of them are conducted by separate boards. GMAT is conducted by GMAC, and the SAT is conducted by College Board.
The requirements for the tests and their formats are available on their respective websites. Each school has different score requirements which can best be obtained from the web pages of the schools that you are choosing to apply to.
Also, note that many schools only accept official score reports sent directly from the test provider and do not accept copies of the score reports sent to you by the providers. This would cost additional money to request a score report to be sent to your school. Make sure you properly utilize and select the right schools for the 4 free score reports that come with your exam fees paid for each of these tests. You may have to fill in the university names and codes that the score report needs to be sent to at the time of registration, at the exam, or after the exam depending on the test you are taking.
TOEFL: Test of English as a Foreign Language
IELTS: The International English Language Testing System
SAT: Scholastic Aptitude Test
ACT: American College Test
GRE: Graduate Record Exam
GMAT: Graduate Management Aptitude Test
LSAT: Law School Admission Test
MCAT: Medical College Admission Test
DAT: Dental Admission Test
PCAT: Pharmacy College Admission Test
OAT: Optometry Admission Test