Chungin is a term used in Korean history to describe a social class of people who were considered to be between the nobility and the commoners.
Imagine a playground where there are big kids (nobility), little kids (commoners) and some kids who are not as big as the big kids but not as little as the little kids. These "in-between" kids can be called chungin.
In Korea, chungin were usually government officials, doctors, scholars, or skilled workers who were respected for their knowledge or expertise, but did not have the same social status or power as the nobility.
Just like how the in-between kids on the playground may have some influence among the big and little kids, chungin had some power and influence in their society, but not as much as the nobility.
Chungin were also sometimes discriminated against or looked down upon by the nobility, just like how some big kids may not want to play with the in-between kids on the playground.
Overall, chungin were an important part of Korean society, occupying a unique social position between the nobility and commoners.