Cultural imperialism is the practice of promoting a more powerful culture over a least known or desirable culture. It is usually the case that the former belongs to a large, economically or militarily powerful nation and the latter belongs to a smaller, less powerful one.
Media imperialism :The process whereby the ownership, structure,distribution or content of the media in any one country are singly or together subject to substantial external pressures from the media interests of any country or countries without proportionate reciprocation of influence by the country so affected (Boyd-Barrett (1977:117
The theory of cultural imperialism was developed in the 1970 by Herb Schiller to explain the media situation as existed at that time. The nature of media at that time promoted a one way, top down transmission system from dominant country to dominated country that theoretically gave rise to a passive audience and a powerful media.
American media critic Herbert Schiller wrote: "The concept of cultural imperialism today  best describes the sum of the processes by which a society is brought into the modern world system and how its dominating stratum is attracted, pressured, forced, and sometimes bribed into shaping social institutions to correspond to, or even promote, the values and structures of the dominating centre of the system. The public media are the foremost example of operating enterprises that are used in the penetrative process. For penetration on a significant scale the media themselves must be captured by the dominating/penetrating power. This occurs largely through the commercialization of broadcasting."
The cultural imperialism theory states that Western nations dominate the media around the would which in return has a powerful effect on third world cultures by imposing them western views and therefore destroying their native cultures. Western civilization produces the majority of the media because it is cheapter for them . Therefore third world countries are watching media filled with the western world’s way of living believing and thinking. The third world cultures then start to want and do the same things in their countries and destroy their own cultures.
The theory says that humans do not have the free will to chose how they feel, act, think and live. They react to what they see on television because there is nothing else to compare it to besides their own lives. . This theory explain that as long as third world countries continue to air western civilization;s programs then the third world countries will always believe they should act, feel, think and live as western civilizations act , feel, think and live. This theory is value neutral and objective. Like neo marxism cultural imperialism is very specific to the time period in which it was being proposed.