Who is Plyushkin from Dead Souls and what is their importance?

Plyushkin is described as an ill-dressed, lazy and grieving landowner. After the death of his wife and son, he ceases to care about his land and it severely deteriorates. As a result, his peasants become lazy, and his estate is decaying. People who don't personally know Plyushkin assume he has mistreated his peasants, and as a result of his inability to care for them, many have died.