Geographic areas that FEMA defines according to varying levels of flood risk. These zones are depicted on Flood Insurance Rate Maps (FIRMs) and determine flood insurance requirements and premiums. High-risk zones (Special Flood Hazard Areas) include Zone A (1% annual chance of flooding) and Zone V (coastal high-hazard areas with wave action). Moderate-to-low risk zones include Zone B, C, and X. Properties in high-risk zones with federally backed mortgages must carry flood insurance. Zone designations directly impact insurance costs and building requirements.