Sodium alginate is a natural polysaccharide extracted from the cell walls of brown algae such as Laminaria and Macrocystis species. It is a linear copolymer composed of β-D-mannuronic acid and α-L-guluronic acid residues linked by 1→4 glycosidic bonds. The compound is extensively utilized in the food industry as a thickener, stabilizer, and gelling agent under the designation E401. In molecular gastronomy, it enables spherification by forming gel membranes upon contact with calcium ions via the egg-box cross-linking mechanism. It produces highly viscous aqueous solutions and is valued in pharmaceuticals for controlled drug release, wound dressings, and tissue engineering scaffolds due to its biocompatibility and gel-forming properties.