Eau de Toilette, Eau de Parfum and Parfum are not three qualities of the same thing. They are three concentrations of fragrance oil in alcohol, and each one behaves differently on skin.
An Eau de Toilette usually carries five to fifteen percent oil. It opens bright, projects well for the first hour or two and then settles close to the skin. In hot weather this is often a blessing: it feels fresh and never heavy, which is why many daytime office scents are EDTs.
An Eau de Parfum sits between fifteen and twenty percent. It lasts longer, often six to eight hours, and the heart and base notes have more room to develop. If you want one bottle that works from the morning commute to an evening out, an EDP is usually the safer choice.
Parfum, also called Extrait, goes above twenty percent. It is the most expensive per millilitre, but you need only a spray or two, it stays for most of the day and it rarely turns sharp in the heat. Decants make Parfum affordable: a 5ml vial of an Extrait can last a month of evenings.
The same name can exist in all three strengths, and they can smell noticeably different. When you compare two of our listings and the prices do not match, check the concentration first. It is printed on every product page next to the size.