The SAT (technically known as the SAT I) is a general test of verbal and quantitative reasoning accepted for U. S. college admissions. The test is required for admission to undergraduate programs of most US universities. Many universities also require you to take SAT-II tests.
SAT-I : Reasoning Test
The SAT-I is a three hour, primarily multiple-choice test that measures verbal and mathematical reasoning abilities that develop over time. Most colleges require SAT-I scores for admission.
SAT-II : Subject Tests
The SAT-II subject tests are one hour, primarily multiple-choice tests that measure your knowledge of particular subjects and your ability to apply that knowledge. Many universities may require you to take this along with SAT-I.
The SAT is developed and administered by the US-based "College Entrance Examination Board". This implies that College board sets the questions, conducts the test, and sends each examine the score report.