Postmodernity vs. the Postmodern vs. Postmodernism

Georgetown university, in Washington DC has online faculty page on "Po-Mo". It discusses Postmodernity, the Postmodern & Postmodernism in sections. It approaches different aspects of all of these from many different angles.

It defines Post Modernism, as a mix of low (pop) and high culture. The Pop culture element comes from what the majority of the population enjoy (Pop music, the Sun, take away meals) and the high culture comes from what the top percent of the population enjoy (Classical music, Financial times & michelin star restaurants). It tells that designers, at the time, took the decision to reject the modernist values and it's master narrative ideas.
It was a remix trend. It took existing material and re-purposed it; old photos of the stars (seen as low culture) were given a new colour scheme and hung on the gallery wall (high Culture).  Whaam by Roy Lichtenstein references directly action comics of the 1950s (low Culture) and turn it into art (High Culture).

Directly linked to this remix idea, is connected to the idea that the history is not the authority of the current, more a source in order to pastiche, collage and parody. It's purpose; nostalgic or otherwise. In the 21st century, it is a given that everything is post modern & the influence of all of the current trends are already mixed sources, thus making everything and anything post modern.