What are top, middle, and base notes?
Top notes provide the first scent impression of a fragrance once it has been applied to the skin. They are usually lighter, more volatile aromas that evaporate readily. Their scent usually lingers for between 5 and 30 minutes. Middle notes, sometimes referred to as “heart notes”, make up the body of the blend. They may be evident from the start, but will usually take 10-30 minutes to fully develop on the skin. They are the notes that classify the fragrance family (floral, oriental, chypre, etc, see below). Base Notes are those with the greatest molecular weight. They last the longest, and are also important as fixatives, that is, they help slow down the evaporation rates of the lighter notes, giving the fragrance holding power. Common base notes include oakmoss, patchouli, woods, musk and vanilla.
A fragrance which does not have traditional top, middle and base notes is usually described as “linear”.

How long can I keep my perfume before it “turns”?
Some industry experts say that perfume should be replaced every year, but properly stored, perfumes should last much longer. Most perfumes will keep several years, some will keep many more years than that.
To store perfume properly, keep it away from heat and light. A dark closet or a covered box is best. Also avoid direct exposure to air. Splash bottles, which expose the fragrance to air every time they are opened, are problematic. Consider decanting into a smaller atomizer for regular use. If you apply perfume directly from a bottle stopper, wipe the stopper with a clean, lint free cloth before replacing it in the bottle.

What is the difference between essential oil and perfume oil?
Essential oils are volatile, fragrant liquids extracted from plant leaves, bark, wood, stems, flowers, seeds, buds, roots, resins and petals, usually through steam distillation. In other words, they are raw materials that can be used to create perfumes. They are highly concentrated and apart from a few exceptions, should not be used directly on the skin, although they can be diluted in a carrier oil, such as jojoba, for such use.
Perfume oils are fragrance components, natural or synthetic, in an oily base rather than an alcohol base, and can be used directly on the skin.

What are Eau De Toilette, Eau De Parfum and Parfum.
These terms refer to the strength of the fragrance, or more specifically, to how much high grade alcohol and/or water has been added to the fragrance oils. Parfum (generally the most concentrated form you can buy) has 15-25% perfume oil dissolved in alcohol. Any mixture with a lower proportion of oil to alcohol is an eau (water).
You may also see the term Parfum de Toilette. Most companies use this term to describe a concentration that is either the same as Eau De Parfum, or between Eau De Parfum and Parfum. Other companies use the term to describe an Eau De Toilette concentration.

Eau Fraiche (Usually 3% or less perfume oil)
Eau de Cologne (2 – 5% perfume oil)
Eau de Toilette (4 – 10% perfume oil)
Eau de Parfum (8 – 15% perfume oil)
Soie de Parfum (15 – 18% perfume oil)
PARFUM or Perfume (15 – 25% — also sometimes referred to as extract or extrait)
Perfume oil (15-30% perfume oil in an oil rather than alcohol base)