The notes of a perfume are used to define its stages of scent diffusion.  It is because of these notes that a perfume give off different tones in different times from the moment of application.

The reason for which perfumes are such defined lies in that the essentials contained in each perfume are of different substances, and that each varies in such essential characteristics as density, evaporation, and weight. This perfume composition generally called the fragrance pyramid is made of three notes.   These top, medium and lower notes can be thuoght of as transitionary layers. The top note, also known as peak note, is the first scent sensed upon the application of the perfume.  As it contains the evaporative of the essentials in the perfume, its effect lasts only a brief duration, and its vigor declines within a few minutes.

However, the brief duration of its effect does not imply an ineffectiveness. On the contrary,

as the first fragrance to appeal to the sense of scent of the consumer during the process of perfume testing and selection, it holds an important place in marketing and sales.

In this note of a greeting effect, scents preferred are usually those of citrus and mild flowers

chosen for their refreshing feel.  The middle note, which is also known as the heart note, is -as its name suggests- the heart of the perfume, its key component.

This note determines the general ambiance, ie, the character, of the scent.  It begins to surface once the upper note has lost its effect; and while it would not be possible to indicate a specific frame of time, the effect of the middle note lasts generally for about twenty to twenty-five minutes.  When buying perfume, it is best to give the tested perfume some time for the middle note to manifest itself.  Because it is with this note that the perfume begins to bring out its intended effect.  Fragrances used in this note are aromatic such as in cinnamon, or flowery as in sardinias and ylang ylang.  The lower note, also described as the bottom or base note, enters the picture once the top and middle notes have come in and identified the main theme of the fragrance; and it is responsible for the lasting effect of the perfume.

The fragrance tones in this note manifest themselves approximately half an hour into the spraying of the perfume. They are stronger and more dense and generally last up to seven or eight hours, although depending on the quality of the perfume. In the base note, vanilla usually accompanies scents of cedar and sandalwood.