Perfume is made from about 78% to 95% of specially denatured ethyl alcohol and a remainder of essential oils.
The different concentrations of oils and alcohol are how we get the different classifications of perfume.
More recently very low concentrations of oils have been coming onto the market including Homeopathic compounds said to care for the skin.
- Perfume is made with 22% of essential oils. It is the costliest form of fragrance.
- Eau de Parfum (EDP), ranges between 15 and 22% essential oils.
- Eau de Toilette (EDT) as between 8 to 15% oils.
- Eau de Cologne has just 4% essential oils.
- Eau Fraiche with 1 to 3% essential oils, is the weakest dilution of fragrance.
A modern trend is to produce just Eau de Parfums and not an Eau de Toilette.
Dilution
Perfume oil is necessarily diluted with a solvent because undiluted oils (natural or synthetic) contain high concentrations of chemical components (natural or otherwise) that will likely result in allergic reactions and possibly injury when applied directly to skin or clothing. As well, the scents in pure perfume oils are far too concentrated to smell pleasant. By far the most common solvent for perfume oil dilution is ethanol or a mixture of ethanol and water. Perfume oil can also be diluted by means of neutral-smelling liquid oils such as fractionated coconut oil, or liquid waxes such as jojoba oil.
Intensity & Longevity
The intensity and longevity of a perfume bases on the concentration, intensity and longevity of the used aromatic compounds (natural essential oils / perfume oils): As the percentage of aromatic compounds increases, so does the intensity and longevity of the scent created. Different perfumeries or perfume houses assign different amounts of oils to each of their perfumes. Therefore, although the oil concentration of a perfume in Eau de Parfum (EdP) dilution will necessarily be higher than the same perfume in Eau de Toilette (EdT) from within the same range, the actual amounts can vary between perfume houses. An EdT from one house may be stronger than an EdP from another.
EdP
Men's fragrances are rarely as EdP or perfume extracts. As well, women's fragrances are rarely sold in EdC concentrations. Although this gender specific naming trend is common for assigning fragrance concentrations, it does not directly have anything to do with whether a fragrance was intended for men or women.
Differences
Furthermore, some fragrances with the same product name but having a different concentration name may not only differ in their dilutions, but actually use different perfume oil mixtures altogether. For instance, in order to make the EdT version of a fragrance brighter and fresher than its EdP, the EdT oil may be "tweaked" to contain slightly more top notes or fewer base notes. In some cases, words such as "extrême", "intense" or "concentrée", that might indicate aromatic concentration are sometimes completely different fragrances that relates only because of a similar perfume accord. An example of this would be Chanel‘s Pour Monsieur and Pour Monsieur Concentrée.
Eau de Cologne
Eau de Cologne (EdC) since 1706 in Cologne, Germany is originally a specific fragrance and trademark. However outside of Germany the term has become generic for Chypre citrus perfumes (without fond notes).
Homeopathic
Since 1994 in Germany are produced more than 100 different perfumes basing on natural sources with the feature to be skin protecting: They have ~1% aromatic compounds and are useful as scent with hoemostatic (homeopathic) effects; and ad Jojoba as perfumes, as (herpes-protecting) lip-gloss and as skin-care.
The word perfume used today derives from the Latin "per fumum", meaning through smoke. Perfumery, or the art of making perfumes, began in ancient Mesopotamia and Egypt (left) but was developed and further refined by the Romans and 
