The Graduate Record Examination is a computer-based standardized test required by many graduate programs. The test has three sections: analytical writing, verbal reasoning and quantitative reasoning. A new version of the GRE, called the GRE revised general test, was introduced in August 2011. On the revised general test, you can skip questions.
The GRE revised general test is computer-adaptive by section, which means your performance on your first verbal reasoning or quantitative reasoning section determines the difficulty of the questions on your next section. You can skip questions within a verbal reasoning or quantitative reasoning section, go back and change your answers and even mark questions you want to return to later, according to ETS, which developed the test. You can't move between the two essays in the analytical writing section.
The previous version of the GRE was computer-adaptive by question; the difficulty of each question was determined by your answers on the previous questions. Test-takers couldn't skip questions or go back to change their answers on the previous version of the test. ETS designed the GRE revised general test to be more test-taker friendly.