What Is Vitamin C Serum? Types, Benefits & Stability (2026)
Vitamin C is considered a “must-have” in skincare — shorthand for bright, firm skin. But when you actually go to buy one, it’s confusing. L-ascorbic acid? Derivatives? And then there’s the talk that “it turns brown once you open it.” Why is it so complicated? There’s a reason. Vitamin C is an ingredient whose benefits … Read more