This is the VOA Special English Education Report.

Today we continue our discussion of the academic degrees offered by American colleges and universities. Last week, we talked about the associate, bachelor's and master's degrees.

The highest degree that a student can earn is a doctorate. Some doctorates are professional degrees, as opposed to a degree based on research. Medical students, for example, receive an M.D., from the Latin "medicinae doctor." Future lawyers receive a J.D., for "juris" or "jurum" doctor, meaning a doctor of law or laws.

A PhD graduate from the University of Oklahoma

Someone with a PhD is a "doctor of philosophy." Many people earn a PhD, yet not many are philosophers. The name has survived since the Middle Ages when many areas of study were called philosophy.

Students can receive a PhD in engineering, social work, education, music, history and a lot of other areas. Requirements can differ from one university to another, and from one area of study to another. But the National Science Foundation says American doctoral education is organized around a research experience.

A PhD usually requires at least three years of full-time study after a bachelor's degree. Some people first get a master's degree, other do not.

PhD candidates must also pass special examinations and carry out original research. Students present their findings by writing a dissertation, a long paper that they have to defend before a group of experts.

Every year, the federal government collects information on research doctorates awarded in the United States. More than forty-three thousand students received a research doctorate in two thousand five, the most recent year reported.

Close to one-third of those doctorates went to foreign students in the United States on a temporary visa. The largest numbers came from China, South Korea, India, Taiwan and Canada. Most of them studied engineering, physical science or life science. 

The University of Illinois awarded the largest number of doctorates to foreign students. The other universities in the top five were Purdue, Ohio State, Texas A&M and Pennsylvania State. 

And that's the VOA Special English Education Report, written by Nancy Steinbach. Our Foreign Student Series continues next week. If you missed any of our reports, you can find them at voaspecialenglish.com. And if you have a question about studying in the United States, send it to special@voanews.com. Please be sure to include your name and country. I'm Steve Ember.