These are sometimes known as opening notes or head notes this is because they are the fragrance notes recognised on applying the fragrance. Top notes are the lightest notes of all three and they are the first to fade. They represent the first smell of the fragrance giving you the first impression of the fragrance to entice you to purchase that particular scent.
Typical top notes include citrus such as bergamot, lemon, orange zest, light fruits, anise, berries, grapefruit and fresh herbs such as basil, sage and lavender.