GRE is for those seeking graduate school entry in US and other English speaking countries. Each year, more than 600,000 prospective graduate school applicants from approximately 230 countries take the GRE General Test. Applicants come from varying educational backgrounds and countries, and the GRE General Test provides the only common measure for comparing their qualifications.
GRE is an test format that is required by the graduate schools to check the applicant's verbal reasoning, quantitative reasoning, critical thinking, and analytical writing skills. Therefore you should first decide on the course you want to study and the college you want to join, then go through the prospectus of that college and look for the requirements. There are colleges who accept GRE score for MBA courses also. So you should look for the college and the course before you decide on taking GRE or GMAT or any other ETS's exam.