There are a wide variety of doctoral degrees awarded to students in a number different categories in the United States. Doctorates are not restricted to being based solely on research or academic coursework. The first research doctorate was the doctor of philosophy, which came to the U.S. from Germany, and is frequently referred to by its initials of Ph.D. . As academia evolved in the country a wide variety of other types of doctoral degrees and programs were developed. Some of these included a focus on teaching such as the Doctor of Arts , others were simply a more specific curricula within a specific field such as the Doctor of Engineering or Doctor of Education of which may be identical in requirements, length, coursework and research to the Ph.D.