How do you smell perfume?

The perfume consists of fragrance mixed with alcohol or other solvents. When it evaporates, molecules of the fragrance enter the air. When you inhale, the scent receptor cells in your nose detect the chemical compound, which your brain then classifies by type and intensity. There are smells that are instinctively pleasant (as with pheromones) and some that are intellectually associated (fruit, baked cookies). With perfume, the association could be either, as individuals may react differently to the same smell.