Postgraduate or graduate education refers to academic or professional degrees, certificates, diplomas, or other qualifications pursued by post-secondary students who have earned an undergraduate (bachelor's) degree.

The organization and structure of postgraduate education varies in different countries, as well as in different institutions within countries. While the term "graduate school" or "grad school" is typically used in North America, "postgraduate" is often used in countries such as Australia, Bangladesh, India, Ireland, New Zealand, Pakistan, South Africa, and the United Kingdom.

Graduate degrees can include master's degrees, doctoral degrees, and other qualifications such as graduate certificates and professional degrees. A distinction is typically made between graduate schools (where courses of study vary in the degree to which they provide training for a particular profession) and professional schools, which can include medical school, law school, business school, and other institutions of specialized fields such as nursing, speech–language pathology, engineering, or architecture. The distinction between graduate schools and professional schools is not absolute since various professional schools offer graduate degrees and vice versa.

Producing original research is a significant component of graduate studies in the humanities, natural sciences and social sciences. This research typically leads to the writing and defense of a thesis or dissertation. In graduate programs that are oriented toward professional training (e.g., MPA, MBA, JD, MD), the degrees may consist solely of coursework, without an original research or thesis component. Graduate students in the humanities, sciences and social sciences often receive funding from their university (e.g., fellowships or scholarships) or a teaching assistant position or other job; in the profession-oriented grad programs, students are less likely to get funding, and the fees are typically much higher.

Although graduate school programs are distinct from undergraduate degree programs, graduate instruction (in the US, Australia, and other countries) is often offered by some of the same senior academic staff and departments who teach undergraduate courses. Unlike in undergraduate programs, however, it is less common for graduate students to take coursework outside their specific field of study at graduate or graduate entry level. At the Ph.D. level, though, it is quite common to take courses from a wider range of study, for which some fixed portion of coursework, sometimes known as a residency, is typically required to be taken from outside the department and University of the degree-seeking candidate, to broaden the research abilities of the student.