Barrier islands are coastal landforms that run parallel to the mainland, typically composed of sand and sediment. They serve as a protective buffer against ocean waves and storms, helping to shield the mainland from erosion and flooding. These islands can vary in size and shape and are often home to diverse ecosystems, including beaches, marshes, and dunes. Many barrier islands are found along the Atlantic and Gulf coasts of the United States, such as the Outer Banks in North Carolina and Padre Island in Texas. They are important for wildlife habitats and recreational activities, attracting tourists and providing essential resources for local communities.