Vitamins are organic compounds essential for normal growth and nutrition, typically required in small quantities in the diet. They play crucial roles in various biochemical processes, including metabolism, immune function, and cell repair. Vitamins can be classified into two categories: fat-soluble (A, D, E, K) and water-soluble (B-complex, C). Fat-soluble vitamins are stored in body tissues and require dietary fats for absorption, while water-soluble vitamins are not stored and must be consumed regularly. Natural sources include fruits, vegetables, dairy, and meats. They contribute to sensory characteristics such as flavor and color in food, and are vital for maintaining health and preventing deficiencies.