The associate degree is a two year degree which is earned predominantly at community and technical colleges, although an increasing number of four year schools offer the degree. The degree is commonly awarded in one of three ways: an Associate of Arts, an Associate of Science and an Associate of Applied Science.
The bachelor's degree is the traditional entry-level degree program. It involves a four-year course of study (some science and engineering programs require a fifth year) and generally requires a general education alongside an academic specialization, or major. The common variations of the degree are the Bachelor of Arts, Bachelor of Science and the Bachelor of Fine Arts.
The master's degree is a graduate level degree that generally involves specialization in a subject closely related to that which was studied at the bachelor's degree level. In the United States it is common for a master's degree to require two years of study, though some programs are shorter and some are somewhat longer. Certain disciplines will award master's degrees with slightly different titles; for instance an M.P.P. is a Master of Public Policy, an M.B.A. is a Master of Business Administration and an M.Arch. is a Master of Architecture. It is common for a master's degree program to require a written thesis or research project, especially for students who wish to go on to doctoral work in their subject.
The doctorate is the highest level of academic degree obtainable. It generally involves several years of coursework and several more years of specialized research culminating in a book-length thesis of original academic work that must be defended in front of a committee of academic experts. This degree is almost always called a Doctor of Philosophy, though some disciplines award their own doctorate such as a Doctor of Education, a Doctor of Psychology or a Doctor of Theology.
A professional degree refers to a degree taken after the baccalaureate level which leads to membership in an accredited profession. The most popular professional degrees are the Juris Doctor degree, which allows entry to the legal profession, the Doctor of Medicine, the Doctor of Veterinary Medicine and the Doctor of Dental Surgery.