Groins are structures built along coastlines to control erosion and manage sediment. They are typically made of wood, stone, or concrete and extend from the shore into the water. By interrupting the flow of water, groins help to create a stable beach area and protect coastal properties from wave action. These structures work by trapping sand that is carried by currents, allowing it to accumulate on one side. While groins can be effective in preserving beaches, they may also lead to increased erosion on adjacent areas, as the natural flow of sediment is altered.