The process of perceiving smells. In order to smell things—that is, in order for olfaction to occur—humans use two separate sensory areas. The first is the nasal cavity. Aromas smelled via the nose are said to occur by orthonasal olfaction. The other area is at the cavity at the back of the palate. Aromas perceived this way—retronasally—happen as a result of wine first being warmed in the mouth and mixed with saliva.