This article makes an odd claim about postmodernism: that Internet culture spelled an end to postmodernist theory, partly by materializing it in practice as postmodernity. At times simplistic, at other times suggestive, it's an interesting enough piece to argue with ... and it provides a serviceable general-audience summary of postmodernism as theory and aesthetic:
This is the essence of postmodernism: the idea that there is no essence, that we're moving through a world of signs and wonders, where everything has been done before and is just lying around as cultural wreckage, waiting to be reused, combined in new and unusual ways. Nothing is direct, nothing is new. Everything is already mediated. The real, whatever that might be, is unavailable. It's an exhilarating world, but uncanny too. You look around at your beautiful house and your beautiful wife and you ask yourself, like the narrator of the Talking Heads song: 'Well, how did I get here?"