What component of skin is primarily responsible for its elasticity?

Collagen is the main protein responsible for the skin's elasticity and structure. It serves as a scaffold that strengthens the skin, helping it maintain its firmness and resilience against stretching and sagging. As skin ages or is exposed to environmental stressors, the production of collagen diminishes, leading to a loss of elasticity and increased wrinkles.

Keratin, while important for the protective barrier of the skin, does not significantly contribute to elasticity. Melanin is responsible for skin pigmentation and provides some protection against UV damage, but it does not play a role in the skin's elasticity. Hyaluronic acid acts as a moisturizer, retaining water in the skin, but its primary function is not related to providing elasticity like collagen does. Thus, collagen is the protein most fundamentally associated with the skin's ability to stretch and return to its original shape.