The medium is the message

Postmodernism separates from modernist approaches to create its own perspective. While modernism is simple and sharp, postmodernism is more unique and steps away from the monotony.

Marshall McLuhan coins the phrase The Medium is the Message in his book Understanding Media: The Extensions of Man. What he really means by this phrase is the way information is presented to people will determine how they understand it. When reading a book that is later made into a film, you may find the raw information to generally be the same, but the message is completely different. One allows you to create visuals and see dialogue while the other gives visuals and allows you to interpret the dialogue the way it's presented. This is why people get frustrated when their favorite book becomes a movie. They have already stored the information and understood it from the book and then seeing it in a whole new media, visualized by someone else's understanding of the book, completely sets them off.

How I would connect this to Post Modernism and Modernism would mean that they are simply two different medias. Generally they both apply to the same things: art, music, decor, fashion, architecture etc. But they are two different ways of presenting something. How the person understands it depends on how the information is given to them.