Thickeners, also known as gelling agents, are substances that increase the viscosity of latex and liquids, and are also called paste materials when used in food. Thickeners can enhance the viscosity of a system, maintaining a uniform and stable suspension or emulsion state, or forming a gel; most thickeners also have emulsifying properties. They can be divided into two major categories: natural and synthetic. Natural thickeners are primarily derived from plants and seaweeds containing polysaccharide sticky substances, such as starch, gum arabic, pectin, agar, gelatin, alginate, carrageenan, dextrin, etc. Common gelatin, soluble starch, and polysaccharide derivatives are suitable for cosmetics. Synthetic thickeners include carboxymethyl cellulose, propylene glycol alginate, methyl cellulose, sodium starch phosphate, sodium carboxymethyl cellulose, sodium alginate, casein, sodium polyacrylate, polyoxyethylene, and polyvinylpyrrolidone, among others.