The Caste System is a system used in India that judges people based on their family's status.
Here's how it works:
You are born into a level at birth, and you cannot move up or down. You were basically held to that level, and couldn't do much outside of that level.
The levels are:
Bhramin (Academics, Priests)
Kshatriya (Kings, Queens, and Warriors)
Vaishya (Landowners, and Merchants)
Sudra (Peasants, Commoners, and Servants)
Untouchable (Street Sweeper, and Laterine Cleaner. They aren't even considered to be on the system's chart, but below it.)
To allow people to move up or down in ranks based on their personality, reputation, and what they do. To be placed depending on how good of a person they are, instead of their family.