The SSAT (Secondary School Admissions Test) is a standardized test required for admission to elite independent schools for grades 4-12, measuring a student's math, verbal, and reading skills. It consists of various sections including writing, quantitative, verbal, reading, and experimental, with different formats for elementary, middle, and upper-level tests. To achieve a good score, students should begin preparing at least two months in advance, practice regularly, and focus on improving weak areas while maintaining a steady pace during the exam.