The chemical composition of perfume is generally made up of two components: a base substance and various scented oils. Bases are usually made of a mixture of water (H2O) and ethyl alcohol (C2H6O), while the chemical composition of the oils vary greatly, depending on what the oil was extracted from.
Perfume bases are used to anchor the perfume to the skin while evaporating to spread out the scent. Oils contain the notes, the three scents that make up the complex smell, of the perfume. Natural perfumes usually contain at least three separate oils, while synthetic perfumes usually contain a single chemical compound that composes all three notes.