Vitamins are divided into two categories based on their solubility in water or fat.

(a) Water-Soluble Vitamins: This category includes vitamins that are water-soluble.

B vitamins (B₁,B₂, B₁₂ etc.) and vitamin C are two examples.

(b) Fat-soluble vitamins: This category includes vitamins that are only soluble in fat and not in water. Vitamins A, D, E, and K, for example.

Biotin, sometimes known as vitamin H, is not soluble in water or fat.

Vitamin K is the vitamin that is responsible for blood coagulation.