Breakwaters, jetties, and groins are coastal structures used to protect harbors and shorelines from wave energy. Breakwaters are structures that reflect and dissipate wave energy to shelter harbors. Jetties are narrow structures that project from the shore into water and provide berths for ships. Groins are structures built perpendicular to the shore to trap littoral drift and protect or build beaches. There are different types of each structure based on materials, permeability, and orientation relative to shorelines and water flow.