Undergraduate education refers to the level of education that students pursue after completing secondary education and before earning a graduate degree. It typically involves coursework and training in a specific field, leading to the award of a bachelor's degree or other undergraduate credential.
Graduate education refers to education beyond the undergraduate level, typically consisting of master's and doctoral degree programs. These programs are designed to provide advanced training and expertise in a particular field, and can lead to careers in academia, research, industry, or government.
A PhD, or Doctor of Philosophy, is the highest academic degree awarded in many fields of study. It requires several years of study and research beyond a master's degree, and involves advanced coursework, independent research, and the production of a dissertation that contributes new knowledge to the field.