The biggest organ in the human body is the skin. It serves as a protective barrier that covers the entire body, shielding the internal organs and systems from external elements such as bacteria, chemicals, and physical injuries. Skin plays crucial roles beyond protection, including temperature regulation, sensation, and the production of vitamin D upon exposure to sunlight. It consists of three main layers: the epidermis, dermis, and hypodermis, each with specific functions and structures. Maintaining skin health is important for overall well-being, as it reflects the body's internal state and can provide clues to various health conditions.