Vitamins are typically classified into two groups based on their solubility.

Fat-soluble vitamins- Vitamins A, D, E, and K. They are stored in the body's fatty tissues.

Water-soluble vitamins- Vitamin C and the B-complex vitamins (e.g., B₁, B₂, B₆, B₁₂, niacin, folic acid, biotin, pantothenic acid). They are not stored in the body and are excreted in urine.