sentences:  These notes are created carefully with knowledge of the evaporation process and intended use of the perfume.The presence of one note may alter the perception of another—for instance, the presence of certain base or heart notes will alter the scent perceived when the top notes are strongest, and likewise the scent of base notes in the dry-down will often be altered depending on the smells of the heart notes.The idea of "notes" is used primarily for the marketing of fine fragrances.