A graduate school or "grad school" is a school that awards advanced degrees
The general requirement that students must have earned a previous undergraduate (bachelor's) degree
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.
Those attending graduate schools are called graduate students, or in British English postgraduate students, or, colloquially, postgrads. Degrees awarded by graduate schools include bachelor's, master's degrees, doctoral degrees, and other postgraduate qualifications such as graduate certificates and professional degrees.
United Kingdom - Admission to undertake a research degree in the UK typically requires a good bachelor's degree (at least lower second, but usually an upper second or first class). Students may or may not already have a Master's degree. Doctoral candidates are initially admitted to a Masters in Research Philosophy (M.Phil. or MRes), then later accede to a Ph.D. if they progress well.
United States - Admission to graduate school usually requires a bachelor's degree. High grades in one's field of study are important — grades outside the field less so.
Graduate students often declare their intended degree (master's or doctorate) in their applications. In some cases, master's programs allow successful students to continue toward the doctorate degree. Source wikipedia Read More...