Untouchability is extreme and quiet brutal aspect of caste system. The untouchable cast are located at the bottom of the purity pollution scale in the total caste system.

Such castes are outside the caste hierarchy and are considered to be impure. It was believed that merely the touch of such people pollute the other castes.

The Institution of untouchability is not only limited to the avoidance of prohibition of physical contact but to a broader set of social sanction.