Skin is the protective barrier of our internal systems and the world outside. The ability to touch gives neurons in our skin signals to discover the environment around us. We have the ability to tell texture, pressure, pain, and more due to the sense of touch.
There are several layers that make up our skin. The epidermis is the outermost layer consisting of dead skins cells and melanin to protect us from the sun and give our skin color. The middle layer is the dermis. It is harder (relatively) than the epidermis and contains vital functions like: sweat glands, nerve endings, blood vessels, etc. The subcutaneous tissue is composed of fat and connective tissue. This layer helps our body in regulating temperature and cushions our internal organs from damage.
So how do our bodies know that we are touching something? The Somatic Sensory System. This system is consist of receptors that send and receive messages about your surroundings. There are different kinds of receptors that can tell the difference between pain, temperature, pressure, etc.
Photo – http://www.oprah.com/health/Health-Benefits-of-Touching