Vitamin C (Ascorbic Acid) is one of the most known cosmetic active, often used in 'anti-aging' products, it is prized for its antioxidant, brightening, and firming properties. It helps even skin tone, reduce dark spots and hyperpigmentation, stimulate collagen production, and enhance skin radiance and elasticity. Water-soluble and highly potent, it can be incorporated into creams, serums, toners, gels, masks, after-sun care, and even hair care products to support scalp health and improve hair quality. As a highly reactive ingredient, Vitamin C is sensitive to light, heat, oxygen, and high pH, which can lead to rapid oxidation and loss of efficacy. Its effectiveness depends heavily on careful formulation: it performs best at acidic pH levels (around 2.5–4), should be stored in airtight, opaque containers. Combining it with other antioxidants, such as Vitamin E or ferulic acid in anhydrous formulation, can help stabilize the formulation and preserve its benefits. In cosmetic applications, Vitamin C functions as an antioxidant, pH regulator, and photoprotective agent. It improves skin texture, minimizes fine lines and wrinkles, soothes irritation, and enhances overall radiance. Despite its potency, its instability can make it challenging to formulate, requiring precise handling to ensure maximum efficacy.