Post-Something-ism

In academia, adding the prefix "post" to a movement, theory, genre, etc is quite common. The best way to describe the meaning of "post" in this context is to see that "post" is a synonym for "beyond", building on the innovations, theories, style, etc of the original in such a way as to take it beyond what the original was, creating a new theory, genre, whatever, in the process. See Also Evolving Trope.

Often subverted in academia. Usually when someone is being called a "Post-something", it amounts to strawman.

Examples of Post-Something-ism include:

Postmodernism, (which refers to a large number of loosely connected movements, including, but not limited to the trope used here) gets its name because its goal was/is to move beyond the movement of modernism. An excellent definition of postmodernism (insofar as postmodernism can be defined) is, "an interruption of the modern mythological form."
Bands such as the Foo Fighters and Creed have been called "Post-Grunge" because they borrow various elements of classic grunge, while at the same time experimenting with new elements.
- There's also "post-rock", "Post-punk" and "post-metal", just to add more genres. Oh, and "post-hardcore", too.
  - Don't forget Post-Britpop, ie Coldplay.
- Post-whatever.
Post-Disco, which includes most modern pop music. Hip Hop, most electronica, and progressive R&B just to name a few.
The Other Wiki once had a humorous example in an article named "Post Gangsta Rap", sadly, said article no longer exists, so we don't get an explanation.
Post-Cyber Punk tries to move beyond the cynicism and hopelessness of Cyberpunk in various ways, such as giving hope for the future (The Matrix Trilogy does this with a messiah figure), showing the upside of technological progress, as well as the down side (works that focus entirely on the bright side of cyber-punk technologies are called "cyber prep") or by parodying or deconstructing Cyber punk tropes (Snow Crash and Transmetropolitan come to mind.)
Reconstruction could be said to be "Post-Deconstruction", in that it tries to move the genre beyond the criticism of the deconstruction, while at the same time accepting said criticism.
The Ur Example is Post-Impressionism, a term used by art historians to describe artists like Vincent Van Gogh, Henri Toulouse-Lautrec, or Paul Gauguin, who built upon the innovations of the Impressionists and took painting to new styles of expression. Not so much a cohesive art movement as a bunch of loosely-affiliated, like-minded yet fiercely independent artists.
Many developed nations are said to have "post-industrial" economies, since the service and finance sectors are more important than the industrial sector.
Similarly, certain kinds of products are considered to be Post-Scarcity goods. An excellent example is computer software, which, once written, can be infinitely duplicated at virtually zero cost.