Hamamelitannin is a hydrolyzable tannin, specifically a gallotannin, derived from the bark and leaves of the witch hazel plant (*Hamamelis virginiana*). Its chemical structure consists of two galloyl units linked to a central hamamelose (a sugar) moiety. It is a key bioactive polyphenolic compound responsible for many of the plant's traditional medicinal properties. Its primary applications are in the cosmetic, dermatological, and pharmaceutical industries due to its potent antioxidant, anti-inflammatory, and astringent properties. In skincare, it is widely used as a soothing, anti-redness, and pore-refining agent in toners, creams, and serums. Pharmacologically, it has been studied for its potential in wound healing, protection against UV-induced skin damage, and antimicrobial activity, particularly against biofilms (e.g., in combination with antibiotics for *Staphylococcus aureus* infections). As a natural plant extract component, hamamelitannin is valued for its multifunctional benefits. It helps to strengthen skin capillaries, reduce irritation, and provide protection against oxidative stress. Its use is well-established in products targeting sensitive or acne-prone skin.