The chemical reactions and pathways involving phthalate, the anion of phthalic acid. Phthalic acid diesters are used industrially in the production of a variety of household and consumer goods including plastic polymers, lubricating oils, and carriers for perfumes in cosmetics, while phthalic acid itself is used industrially as a plasticizer. Terephthalate is used in the synthesis of polyethylene terephthalate (polyethene terephthlate, abbreviated PET or PETE), a plastic polymer with many commercial uses.