Erogenous zones are areas of the body when stimulated elicit a physical sexual response. Excitement of these areas causes the heart rate to increase as well as blood flow to the genitalia.
There are two areas that will arouse a person sexually or cause erotic stimuli, the specific and nonspecific zones.
The specific zones are the more intimate parts of the body, the lips, tongue, breasts, nipples, buttocks, penis, and vulva, and only in these areas will the body produce a high arousal response rate to an action potential in virtually everyone, meaning even the thought of contact of these spots can cause arousal. This is not to same for the nonspecific spots.
Some of the more common examples of nonspecific spots are;
Ears- The earlobe and behind the ear.
Neck- The clavicle and the nape of the neck.
Arm- The wrist and area connected to the palm, and all along the inside of the arm.
Navel- Near and around the belly button and especially below it.
Waist- On the sides up to the ribs and the small of the back.
Legs- On the inner thigh, behind the knee, along the calf, and around the ankle.
Feet- Bottoms of the feet and toes.
Generally regarded as private these areas although left naked are areas people tend to prevent contact within those areas by people whom they are unfamiliar with because of their sensitivity.
Nonspecific erogenous zones do not produce such a heightened degree of sexual stimulation across the board. An exaggerated, or anticipatory response is responsible for the heightened sense in these areas, and not because there is an increased amount of touch-sensitive receptors like in the area of the specific zones. In addition, everyone has different nonspecific zone that are going to be active, a person might have only one or two "hot spots", or zero depending on the person.
Our brains are very powerful organs, and the most powerful erogenous zone is a person's imagination, making it possible for stimulation achievable outside of direct contact by visual and conversational stimulus without ever being touched. Smells and memories often cause arousal.
Research has shown there are health benefits from a hug or touch and other turn-ons, resulting in the release of oxytocin, dopamine, and serotonin, and in a reduction in stress hormones.