This passage discusses the human skin and its functions. It is the body's largest organ, covering an area of about 21 square feet. Skin forms a protective barrier between the body's internal and external environments. It is composed of three layers - the outer epidermis, middle dermis, and inner subcutaneous fat layer. Touch is one of the most essential senses, as demonstrated by experiments showing babies who lacked skin stimulation failed to thrive. The passage explores how skin detects pressure, temperature, pain, and other sensations through networks of nerve cells and signals to the brain. It is constantly regenerating and repairing itself from minor wounds or burns.