Postmodemism is most often applied as a page design technique by graphical artists and media corporations. These two areas more than any other value graphical density and "form over function" design. Frequently the content of the site is inextricably tied to the design of each pseudo-page; it is hard to categorize these sites into "pages" as they may only exist on one actual HTML page, or rely on hundreds of frames. In the extreme, the content is the design, a cyclical fusion of design for design's sake that may actually stray into postmodernism.
Rarely, postmodemism is used by Russians to create nearly impenetrable Flash game-like things. These typically feature a complete lack of instructions, gears, and a bloooming flower.
Postmodemism, as all things on the Internet, has several different theories as to its origins. The first son of a bitch to design a web site entirely in Flash is widely credited with the creation of postmodemism, but the identity of this first designer is in dispute. Slashdot historians believe that a Macromedia employee Joseph Stanton was the first to use his company's product to contain the entirely of his personal site, a 600-megabyte behemoth that resulted in several death threats upon its debut in 1999.
The movement was christened by the other great Internet movement of the early 2000s, emo kids. Their love of masturbatory art design and using the appellation "postmodern" allowed the name "postmodemism" to sweep across LiveJournal and, inexplicably, escape to the adult Internet in late 2001.
The postmodem world is not strictly tied to the tools used to create the page. In early 2002 the first attempt at a text-only postmodem page went up at TimeCube.com. Although quite large, unconfirmed scientific studies indicate that it would be possible to load the page on a 56k modem in our lifetimes.