Varna refers to the categorization of the Hindu society by four castes, hypothesized by the Brahmins and their sacred texts. The four varnas, or chatur varna, are mentioned in ancient texts in the following (stratified) order, from top to bottom:
the Brahmins: vedic priests
the Kshatriya: kings, governors and soldiers
the Vaishyas: cattle herders, agriculturists and merchants.
the Shudras: labourers, artisans and service providers.
the Outcastes: leather workers, waste removers and foreigners.
The first three varna are considered Arya, and thus allowed to participate in Vedica rituals from which the non-Arya Shudra varna is excluded.