Agar is extracted from an algae (agarophytes, belong to the Rhodophyta (red algae) phylum, primarily from the genera Gelidium and Gracilaria).
Agar or agar-agar is a jelly-like substance. Agar is the mixture of two components, agaropectin (D-glucuronic acid and pyruvic acid) and the polysaccharide agarose.