Polyester is a manufactured fiber formed from any long-chain synthetic polymer consisting of at least 85% the ester of a substituted aromatic carboxylic acid, including (but not limited to) substituted terephthalate units and para-substituted hydroxybenzoate units. Polyester comes in numerous types, depending on the chemistry used in production. All polyesters are inert. They offer a wide range of performance features, but because they are inert, they are not easily modified. Polyesters are oleophilic (having a strong affinity for oils) and must be treated with a soil-release chemistry to prevent soiling and body-odor retention. Along with nylon, polyester is important in apparel, home, commercial, and industrial markets.