Agar is a galactose polymer obtained from the cell walls of some species of red algae or seaweeds (Sphaerococcus Euchema and Gelidium species), chiefly from eastern Asia. Also known as Kanten, Agar-Agar, or Agal-Agal (Ceylon Agar).
Dissolved in hot water and cooled, agar becomes gelatinous; its chief use is as a culture medium for microbiological work (e.g. agar plates). Other uses include as a laxative, a vegetarian gelatin substitute - a thickener for soups, in jellies, ice cream and Japanese desserts such as anmitsu, and as a clarifying agent in brewing.
See also: agarose