Sargassum is a genus of brown (class Phaeophyceae) macroalgae (seaweed) in the order Fucales. It used to be used for alginate extraction. Alginates, derivatives of alginic acids, are used commercially for toothpastes, soaps, ice cream, tinned meats, fabric printing, and a host of other applications. It forms a stable viscous gel in water, and its primary function in the above applications is as a binder, stabilizer, emulsifier, or moulding agent.

Sargassum is also cultivated and cleaned for use as an herbal remedy. Many Chinese herbalists prescribe powdered Sargassum-to be dissolved in warm water and drunk as a tea. It is called "hai zao" in Traditional Chinese Medicine, where it is used to resolve "heat phlegm."