Kelps are large seaweed or brown algae that can be found in the cold, nutrient-rich waters of the world's oceans. There are several synonyms for kelps, including fucus, bladderwrack, wrack, tangle, and seawrack. These plants are important for the ocean ecosystem as they provide habitats for many marine animals and protect the coastline from erosion. They are also used for food, medicine, and extraction of alginates that are used in a variety of industrial products. Kelps have a unique appearance and are easily recognizable with their long, leaf-like fronds that can grow up to several meters in length.