The processes of smelling and tasting are complex. They begin when molecules are released by substances that stimulate the sensory cells in the nose, mouth, or throat.

Olfactory nerve cells are stimulated by odors. They are found in tissue located high inside the nose, and connect directly to the brain.

Gustatory nerve cells are stimulated by the taste of food and beverage. They are located in the taste buds of the mouth and throat.

These sensory cells transmit messages to the brain through the nerves, where specific tastes and smells are identified.

Another chemosensory process, called common chemical sense, also contributes to smell and taste. These cells alert the brain to sensations such as heat (as from peppers) or cool (as from menthol).

The four basic taste sensations are sweet, sour, bitter, and salty.

When these tastes, along with texture, temperature, and information from the common chemical sense, combine with odors, the perception of flavor occurs. Flavor defines the food that is eaten, and is recognized mainly through the sense of smell.