The GRE Subject Tests are achievement tests that measure your knowledge and skill level in a particular field of study. They’re intended for students who have an undergraduate major or extensive background in one of the following disciplines:
These tests are given separately from the GRE General Test and require additional fees of US $ 150. Check with the graduate schools to which you are applying to determine whether any of these extra tests are required. You must take these tests only if a university asks for them. Moreover, it is mainly taken by those students who wish to specialize in explicit areas like Math, Physics, etc.
The GRE Subject Tests are offered up to three times a year in September, October, and April at paper-delivered centers worldwide.