Vitamins can be defined as the essential dietary factors required by an organism in minute quantities and whose absence causes specific deficiency diseases. Vitamins are broadly classified into two types:-

(i) Fat-soluble vitamins:

These are oily substances not readily soluble in water. These include vitamins A, D , E and K.

(ii) Water-soluble vitamins:-

Vitamins that are soluble in water belong to this group. For example :B group vitamins (B₁ ,B₂ ,B₆, B₁₂ ,etc.) and vitamin C.

Vitamin K is responsible for the coagulation of blood.

Vitamin H (Biotin) as an exception, it is neither soluble in water nor in fat