Barrier islands are migrating islands composed of unconsolidated sediment (mainly sand). They are located off the coast, separated from the mainland by marshes, estuaries, and sounds. Due to their sediment composition, barrier islands are constantly reshaped by winds, currents, waves, tides, and storms. The primary function of barrier islands is to act as a natural buffer to the mainland, protecting it from the energy of the sea. There is a large attraction to these beautiful ecosystems and they are often developed and inhabited. Since these islands are constantly migrating, human use is often incompatible with their natural existence. Attempts made to stabilize these islands often results in a weakening of their natural defense mechanisms, via erosion, inlet migration, and littoral drift. Although barrier islands occur throughout the world, the majority lies along the Atlantic and Gulf coasts.