This chapter has examined one the two so-called "minor senses," olfaction. You should now have a deeper appreciation of the important roles that odors play in our everyday lives. The biological machinery underlying odor perception is unique, compared to vision, touch, and hearing, in that olfactory receptors are constantly dying and being replaced. Olfaction also seems tightly linked to parts of the brain responsible for emotional reactions and for memory. One of olfaction's chief functions is to work in concert with its chemical sense companion, taste, to specify the flavor of foods. It is smell's chemical sense companion to which we turn in the next and final chapter.