Sedges are perennial, less often annual herbaceous plants. Sedges are widespread throughout the world and can be found in all climatic zones. More than 5300 species are known worldwide. Most species are relatively common in wet, open areas and on the shores of water bodies. Sedges serve as habitat and food for many animals, especially water birds. Many sedge species serve as an indicator of groundwater depth. Sedges are great water purifiers, just like bulrush and reeds. All large sedges have a durable fibre and they can be used for making bags, carpets, mattresses, and other materials.