How do you get a monopoly in the game?

Please clarify which game you are asking about. "Monopoly" can refer to:

* The board game Monopoly: In this game, you achieve a monopoly by owning all the properties in a color group.

* The concept of monopoly: This refers to a situation where one company or entity has exclusive control over a particular product, service, or market.

Please specify the game you are referring to so I can give you a more accurate answer.