"Stearic acid (first syllable pronounced either steer or stair) is the saturated fatty acid with an 18 carbon chain 
and has the IUPAC name octadecanoic acid. It is a waxy solid, and its chemical formula is CH3(CH2)16CO2H. Its name comes from the Greek word στέαρ "stéatos", which means tallow. The salts and esters of stearic acid are called stearates. Stearic acid is noteworthy as the most common saturated fatty acid, another common one being the C16 compound palmitic acid."
"Generally applications of stearic acid exploit its bifunctional character, with a polar head group that can be attached to metal cations and a nonpolar chain that confers solubility in organic solvents. The combination leads to uses as a surfactant and softening agent. Stearic acid undergoes the typical reactions of saturated carboxylic acids, notably reduction to stearyl alcohol, and esterification with a range of alcohols."