Geranyl pyrophosphate (GPP), also known as geranyl diphosphate (GDP), is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of farnesyl pyrophosphate, geranylgeranyl pyrophosphate. These species are respectively precursors to sesquiterpenes and diterpenes. Geranyl pyrophosphate (GPP), also known as geranyl diphosphate (GDP), is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of farnesyl pyrophosphate, geranylgeranyl pyrophosphate. These species are respectively precursors to sesquiterpenes and diterpenes.