The integumentary system refers to the skin's outer layer.
The integumentary system includes the glands that are connected to the skin (epidermis, dermis, and hypodermis), hair, and nails.
This system performs a variety of complex tasks in addition to functioning as a barrier, such as controlling body temperature, protecting cell fluid, producing vitamin D, and detecting stimuli.
The integumentary system is the largest system in the human body.