The expected release this afternoon of the report by the President's review group on the National Security Agency's (NSA) mass surveillance programs will, we hope, spur a deeper discussion about government secrecy, including issues with our classification system. To help people who might not be as familiar with some of the terms regularly used by those who work on classification policy, we have put together some basic slides to explain the differences between information that is properly marked and appropriately classified and between original and derivative classification. We have also put together a slide explaining overclassification. Click "Read More" to see the slides.