Perfume is a scented liquid worn on the skin to impart a pleasant odor. Originally intended to mask unpleasant body odors, today it is worn to entice the opposite sex, to make a personal statement, or simply to please the wearer. It's made up of animal and plant-based aromatic compounds, dissolved in a mixture of alcohol and water. The amount of scented matter to solvent determines whether the blend is a perfume or a cologne. The aromatic portion can be botanical essential oils, animal musk oils, or nowadays, synthetic scents derived from various chemicals.
The highest proportion of scent is found in true "perfume" — anywhere from 25 to 40% is pure scent. This form is rarely sold, since it is prohibitively expensive and, frankly, far too easy to "overdo." Most consumers are more familiar with eau du parfum, which is 15-30% aromatics.
Eau du cologne and toilet water are more lightly scented products. Originally, eau du cologne referred to a specific citrus-floral blend made in Cologne, Germany, that had a lighter scent and could be applied more liberally. It was a type of toilet water, which has 5-15% aromatic compound, but over time, the terms became largely interchangeable. Because cologne came to mean what toilet water originally meant, today most people use toilet water to refer to an even lighter scent, one with only 3-5% aromatics. Toilet water is sometimes thought of as a "splash" that can be liberally applied after bath or shower.
Another type is perfume oil, which is similar to perfume, with the exception that the solvent is oil-based rather than alcohol-based. It is preferred by people with dry skin who find the alcohol in most scents too drying. Oil-based products can be formulated into a solid material with the addition of a little melted beeswax, to make a waxy block that can be rubbed on the skin. Solid perfumes are often molded into pillboxes or tiny compacts to fit easily in a handbag for on-the-go applications, but they should not be left in the car on a hot day.