What is a caste?
In India a caste is a division of society based on occupation and family lineage.
If someone is not in the top four castes they are believed to be less than human. They are called Dalits and are expected to do demeaning jobs such as disposing of dead bodies and clearing of sewers.
Even though the caste system has been outlawed Dalits are still attacked on a regular basis and often have their houses burnt down.