The main function of hair in humans serves various purposes, including protection, insulation, and sensory input. Hair acts as a barrier against external elements such as dust, dirt, and UV radiation, helping to protect the scalp and skin. It also aids in regulating body temperature by trapping heat. Additionally, hair enhances the sense of touch, as hair follicles are connected to nerve endings that can detect movement. Furthermore, hair plays a role in social and cultural identity, contributing to self-expression and aesthetic preferences in human behavior.