This article is from the Medical Education FAQ, by eric@wilkinson.com (Eric P. Wilkinson, M.D.)with numerous contributions by others.
In spite of its resemblance to the words "U SMILE," it's not a happy
thing. USMLE stands for United States Medical Licensing
Examination, and the website may be found at <http://www.usmle.org>.
There are three parts to it (the first two parts consisting of a
one-day, eight-hour exam and the third part consisting of a two-day
exam), and in virtually every state you must pass the parts in order
to get licensed. The examination is now offered on computer at
testing centers, and may be taken whenever the student wishes. See
the USMLE web site for more information.
The parts are:
Step I, taken after your second year
Step II, taken in your fourth year
Step III, taken at the end of your internship year
 
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