The Hindu caste system is a social hierarchy that determines one's occupation and status at birth. It restricts marriage, occupation choices, and social contact between castes. The four main castes are Brahmins who are thinkers, Ksatriyas who are rulers and warriors, Vaisyas who are merchants and farmers, and Sudras who perform manual labor. Those outside the caste system are known as Dalits and perform undesirable jobs involving pollution. The system aims to help each caste fulfill their duties while maintaining social order and separation between groups.