A grauate school or ("grad school") is a school that awards advanced degrees, such as doctoral degrees with the general requirement that students must have earned a previous undergraduate (bachelor's) degree. Many universities award graduate degrees; a graduate school is not necessarily a separate institution. Original research experience is often a significant component of graduate studies, including the writing and defense of a thesis or dissertation. The term "graduate school" is primarily North American. It also does not usually refer to medical school (students are called "medical students"), and only occasionally refers to law school or business school.