Zamindar means a man of the land or Landlord. They were sort of a micro-king who ruled their small territory by collecting taxes, running a court to resolve disputes, maintaining a military and building palaces. In most cases, they had to share a big chunk of their taxes with the Lord above them (possibly a local king). Just like you would pay income taxes to your government, you will pay taxes to your local Zamindary, who will have a big control over your life.

The core of it is money: Zamindari is a system of collecting taxes.

Some sort of a Zamindari system was always there in most parts of the world. The present Zamindary system was created by the Mughals who replaced the earlier tax collections systems and appointed their own collectors. These collectors were responsible for the local law and order. Unless things got worse they would not call the king and its troops to maintain the local order. In the name of maintaining order, they could kill, rape and plunder - like any other monarch in the world.
 

British era

East India Company and British Crown tried to keep existing systems as much as possible. They