Erosion is the gradual wearing away of rock, soil, or land by natural forces like water, wind, or ice. When rain pounds against a hillside, it slowly carries dirt downhill. When waves crash against cliffs year after year, they chip away pieces of stone. When wind blows across a desert, it picks up sand and reshapes dunes. All of these are examples of erosion at work.

Erosion happens slowly, often too slowly to notice day by day, but its effects can be dramatic over time. The Grand Canyon was carved by millions of years of erosion from the Colorado River cutting through rock. Beach erosion can eat away at coastlines, sometimes threatening houses built too close to the water. Farmers worry about soil erosion because rain and wind can carry away the rich topsoil their crops need.

People sometimes use erosion figuratively to describe things gradually wearing away: trust can erode in a friendship after too many broken promises, or a leader's authority might erode after repeated poor decisions. The verb form is erode, as in “constant criticism began to erode her confidence.” While erosion can create beautiful landscapes like canyons and valleys, it can also cause problems when it happens too quickly or in the wrong places.