Setting aside law and various medical schools, there are two basic types of graduate school programs: master's and Ph.D. Students specialize in a specific area, researching and refining their knowledge, but the focus and intensity differs according to the program. Master's programs tend to be more career oriented.
Master's programs usually take one to two years to complete and, depending on the discipline and the student's motivation, they can confer a significant advantage in the workplace. In general, a biologist with a master's degree will be more desirable and earn a higher salary than one with a bachelor's degree. In some fields, it's difficult to be hired or to advance without those fancy letters - M.A. (Master of Arts) or M.S. (Master of Science) - after your name.
That said, some students opt for grad school because they're not quite sure what to do after college graduation. After all, they've been students all their lives. But two years of specialized study in a field that may or may not turn out to be the career path they want is an expensive gamble.
