This is the first aroma you notice when you smell a blend. That’s because the molecules are evaporating more quickly than the others in the oil. It’s usually a light, fresh, sharp scent—like a citrus. In fact, the citrus oils are all top notes
Middle notes have a very full, soft, character that gives a blend a lot of heart. This is why they’re sometimes called “heart notes!” Some people have an easier time identifying top and base notes, rather than middle notes, partly because middle notes can include both top and base aromas within them. Imagine top notes as a bright citrus tea, and base notes as a dark root tea. Middle notes would be a full-flavored, floral tea with hints of roots and maybe a little orange peel.Base notes
Base notes are intense, earthy, deep, and warm. They create the “undertones” of a blend. This doesn’t mean you won’t notice them as they have a very strong presence, it just means that they may be the last aroma you notice when smelling a blend, or the deepest aroma giving weight to the other scents. This is because base notes evaporate more slowly than top notes.