Sea level refers to the average height above or below which land is measured when describing a coastal area. It serves as a reference point for measuring changes in sea levels caused by natural events such as tides, storm surges and human activities like land reclamation and groundwater extraction.
In practical terms, it's also used to determine the height of buildings or infrastructure that must be built above sea level to avoid flooding during extreme weather conditions or high tide. For instance, building codes in coastal areas often require structures to be constructed at least several feet above sea level to minimize damage from storm surges and rising water levels due to climate change.
In summary, "sea level" is a term used to describe the average height of the ocean's surface or land along a coastline, which serves as a benchmark for measuring changes in elevation and building structures safely above potential flood zones.