Perhaps of all the beauty categories, fragrance is the one that holds the most mystery. It also can be an intimidating space with specific vocabulary. Here to make your life easier are the definitions of two terms that are bandied around but sometimes confused:
Sillage: This is how much a fragrance projects or trails the wearer. Certain natural ingredients have incredible sillage such as patchouli, woods and resins. Of all of our scents Raven, a peony-patchouli, has the greatest sillage.
Longevity: Sometimes confused with sillage, longevity is how long a scent lasts. For example, Myth, a warm white musk, has excellent longevity (about 6 hours, give or take) but low sillage. It's what I like to call a skin scent in that it envelops and lingers close to the skin.