How were people placed in a caste system during hinduisim?

In Hinduism, the Caste System traditionally categorizes people into four main groups, known as varnas: Brahmins (priests and scholars), Kshatriyas (warriors and rulers), Vaishyas (merchants and farmers), and Shudras (laborers and service providers). This classification is believed to be based on factors such as occupation, social function, and spiritual purity, with individuals often assigned to a caste based on their birth. Over time, this system became more rigid, leading to the emergence of numerous sub-castes or jatis, which further stratified society. While the caste system has deep historical roots, its relevance and application have evolved, with significant social reforms advocating for equality and the abolition of caste-based discrimination in modern India.