Publisher Summary There are many gums with similar properties but often with different degrees of technical development and cost effectiveness. As a result, the suppliers and users of gums realize that certain hydrocolloids are preferred in certain end uses. This chapter presents some insight into the selection of alginate as the preferred hydrocolloid in certain applications and explains how that is related to cost-effective functionality. The algin in the seaweed behaves as a cation-exchange material. Algin is present as a mixed salt of alginic acid with enough calcium ions to render it insoluble. The chapter discusses the general format for alginate extraction processes. Alginate solutions lose their viscosity as the temperature of a solution is increased. Loss in viscosity with increased temperature is common to most polysaccharide solutions. Alginates have film-forming and fiber-forming properties. Soluble films or fibers are usually made by removal of water, either by evaporation or exchange with a water-miscible solvent such as acetone or isopropanol.