**Abstract**

Vitamin C, an essential water-soluble vitamin, is known for its pivotal role in various biological functions. This chapter provides an overview of vitamin C, focusing on its chemical structure and synthesis, its multifaceted biological functions within the body, and its remarkable role as a powerful antioxidant. The significance of vitamin C in maintaining immune function, its contributions to collagen synthesis, and its involvement in cognitive health are explored. Moreover, the dual nature of vitamin C as both a pro-oxidant and an antioxidant is highlighted, emphasizing its broad impact on health and well-being. This comprehensive examination of vitamin C underscores its critical role in safeguarding against oxidative damage-related diseases and supporting overall health.

**Keywords:** vitamin C, ascorbic acid, deficiency, antioxidant mechanisms, immune function
