A gelatinous material derived from algae, specifically used as a culture medium of bacteria and other cells for diagnostic or laboratory experiments purposes.
Agar came from the cell walls of red algae, especially those in family Gelidiaceae and family Gracilariaceae. The gelatinous material is extracted by boiling and filtration. The agar is made up of agarose and agaropectin.
Word origin: From Malay agar-agar (jelly)