feudalism is a system based on hierarchies of land ownership.
Ownership of land was vested in the king or Monarch or Emperor who also controlled all the users of the land. The land owners sublet the land to their subjects who must in turn, render services such as work for certain days for the land owners, fight on his behalf, etc.
Feudalism was first practised in ancient Europe from A.D.476 to AD 1500. Examples could be found in ancient India, China and Japan. It was also practised in Asia and Africa.