In France, a DEA (full name: diplôme d'études approfondies, or "diploma of advanced studies") is a (now former) postgraduate degree.
The DEA was a 1-year diploma taken after a maîtrise (4-year undergraduate program) or an engineering school (see grande école) prior to entering a doctorate program.
In the hard sciences, in generally consisted of a number of courses, with examinations and grades, followed by an internship in a scientific laboratory. The students would then write a short thesis about the scientific work they did in their internship, and defend this thesis in front of a committee. The grades of the examinations and, if possible, the internship, were used to rank students in order to select those eligible for funding for doctoral studies. Students that would follow up with a Ph.D. would generally do it in the same laboratory as their intenrship.
DEAs are now subsumed into research-oriented Master's degrees.