Barrier islands are long, narrow, offshore landforms made of sand and sediment that run parallel to the coast. They act as protective barriers against storms and waves, shielding the mainland coast from erosion. Barrier islands are dynamic systems, constantly reshaped by wind, waves, and tides, and are significant in coastal ecology and geology.
Source Stutz, M. L., & Pilkey, O. H. (2011). “Open-Ocean Barrier Islands: Global Influence of Climatic, Oceanographic, and Depositional Settings.” Journal of Coastal Research, 27(2), 207-222.