Alginic acid, also called algin or alginate, is a viscous gum that is abundant in the cell walls of brown algae. It ranges from white to yellowish-brown, and takes filamentous, granular and powdered forms.

Calcium alginate is an water-insoluble, gelatinous, cream coloured substance that can be created through the addition of aqueous calcium chloride to aqueous sodium alginate. Adding artificial flavours and colours creates a more tasty edible slime.

Potassium alginate is a chemical compound that is the potassium salt of alginic acid. It is an extract of seaweed. Its empirical chemical formula is KC₆H₇O₆.

The chemical compound sodium alginate is the sodium salt of alginic acid. Its empirical chemical formula is NaC₆H₇O₆. Its form as a gum, when extracted from the cell walls of brown algae, is used by the foods industry to increase viscosity and as an emulsifier.