Varna is the formal division of social classes in Hinduism, which means Order or Class. People usually confuse it with the word Casta, which is a hierarchical system of a race classification and was created much later by Spanish elites. The system of classifying people into Varnas is much older, and its origins are from India. The main purpose of Varna is a classification of social classes. The Varna system divides four main social classes where people belong: Sudras, Vaishyas, Kshatriyas, and Brahmins.
Each Varna has a specific purpose in the society. Although some Varnas are less “aristocratic” than the others, in Hinduism every Varna is equally important and respected in the whole society. Regarding Hindu beliefs, if one of the Varnas did not exist the others would not be able to function, and the whole society would collapse. This is the main reason of equally giving importance to all of them.
Sudras: most of the people in the world are Sudras. These people usually provide any services, laborers waiters, servants, machinists, fitters, etc… They mainly work for others.
Vaishyas: there are fewer Vaishyas in the world than Sudras. These people usually belong to modern “middle classes.” They are merchants, businessmen, employers, and people who besides themselves provide jobs to others.
Kshatriyas: Only a few people in the world are born Kshatriyas, though a lot of people pretend to be them. These people are true rulers, warriors, leaders, and activists. These people always fight for justice and are mostly selfless. They devote their lives to specific purposes and never go after their ego and benefits.
Brahmins: These people are priests, teachers, scholars, scientists. By quantity, they are less than Kshatriyas. One has to live through long and cruel reincarnations to have a chance to be born a Brahmin.
In the end, it does not matter what people truly want to become in their lives or in what category they want to fit in, if you are born Sudra, Vaishya, Kshatriya or Brahmin you can never change it. Not in this life.