This course assumes knowledge and understanding of the regulations guiding the National Flood Insurance Program (NFIP) and the relevant insurance requirements as examined in the course ‘Understanding the NFIP.’ With that information as background, we move forward into the mapping of floodplains. Since the earliest days of the NFIP there has been a need to revise, update, and correct issues and mistakes on flood maps. Since the federally issued Flood Insurance Rate Map is a legal document, we must understand how to modify that document when we find errors or when conditions represented on the map have changed. Because they are updated periodically, application forms for revising, modifying, and correcting maps are identified in this course but not discussed in any detail. Instead, this course integrates both technical and legal aspects of mapping, to provide an understanding of the technical and regulatory basis for appropriate mapping and map change application approvals.