Babies need touch to develop normally. Massage is universally done and provides relaxation and relief from pain. Hugs give comfort in times of loss. Little kids often have a favorite blanket or stuffed animal to help them sleep better. Petting the soft, smooth fur of a pet gives a sense of calm and comfort. I know I used to fall asleep as a small child when someone brushed my hair.
I recently saw an interview of Eva Detko, a psychotherapist, who shared a simple technique to calm the nervous system by stimulating receptors on the skin. Some of these movements are also done regularly in my qigong classes, which I found very interesting. One technique involves stroking the face from the sides of the nose, upward to the forehead and then going down the sides of the face. The second technique is stroking the shoulders down to the elbows, like you are hugging yourself. The third technique is rubbing your hand from the heel of your palm to the fingertips. There wasn't a prescribed number of strokes and you could also add positive affirmations as you are doing these techniques, such as "I am okay," "I am fine," or "I appreciate and love myself." Apparently, these techniques open up the brain to consolidate the nervous system in a positive way. At any rate, it does feel nice.
From a documentary I saw a long time ago on the power of touch, trust increases when a connection of touch is introduced. People will tend to help you more when they feel your touch. There was an experiment done when someone planted a dime in a phone booth coin return slot then waited until a person came to use the phone. Back in the day when there were phone booths, everyone would check the coin slot to see if someone forgot their dime. When the person found the dime, they would pocket it. Then when the experimenter came to talk to them after making a call and asked if a dime was found in the slot, if the experimenter touched them lightly on their forearm to get their attention, they would return the dime. If the experimenter didn't touch them, they said they didn't find anything in the slot. Waitresses have often used this power of touch to get a better tip from customers in the past.
As a physical therapist, I have a license to be able to touch people unlike many other professions where you must be very careful about touching others. I do know that people will often tell me things that they have never told anyone, including their spouse. I know it's because touch makes people feel safe, it's a very intimate form of communication. It is something that makes us feel connected to each other.