What is the largest organ in the human body?

The skin (integumentary system) is the largest organ by both area and weight. In an average adult it covers approximately 1.5–2 square meters and weighs about 3.6 kg (roughly 16% of body weight). It consists of three layers: the epidermis (outer barrier), the dermis (collagen, elastin, blood vessels, nerves), and the hypodermis (fat and connective tissue). Skin regenerates entirely every 27–30 days, shedding roughly 30,000–40,000 dead cells per hour. It serves critical functions: protection against pathogens, UV radiation defense, temperature regulation through sweat (~2–4 million sweat glands), sensation, and vitamin D synthesis.