What is monopoly? Why a monopolist is referred as price maker?

Watch the following video(s), which you can access in the Weekly Media object or by clicking on the link(s) below: and answer the question.

http://www.youtube.com/watch?v=WbE2USh7RKI&list=SP61533C166E8B0028&index=15:

 

Q1 What is monopoly? Why a monopolist is referred as price maker? Using marginal principle, explain with help of graph, to maximize profit how price-output relationship is achieved by a monopolist