Coast

A coast, also called the coastline, shoreline or seashore, is the land next to the sea or the boundary line between the land and the ocean or a lake; Earth's coastlines run to roughly 620,000 kilometers in total. Coasts are shaped by the topography of the land behind them and by the erosive action of water, especially waves, with the local rock and soil determining what kind of shore results. Larger waves carry more energy and move more sediment, and a long, gently sloped shoreline lets that energy spread out while a short, cliff-lined coast concentrates it and erodes faster, so a coast becomes either a depositional or an erosional environment depending on wave strength and sediment supply; tidal range further shapes the coast, with geologists distinguishing macrotidal, mesotidal and microtidal coasts by how much the tide rises and falls. A coast is a dynamic environment in constant change, driven by sea level shifts, weather and ongoing geological processes, and it now draws roughly 44 percent of the world's population to live within 150 kilometers of it.