Sea level refers to the average height of the ocean's surface, measured over a long period. It serves as a baseline for determining elevation and depth on Earth. Changes in sea level can occur due to various factors, including climate change, melting ice caps, and ocean currents. Monitoring sea level is crucial for understanding environmental changes and predicting the impact of rising waters on coastal areas. Organizations like the National Oceanic and Atmospheric Administration (NOAA) and the Intergovernmental Panel on Climate Change (IPCC) study these changes to inform policy and protect vulnerable regions.