Separating structure from style and behavior was the web standards movement’s core revelation, and each generation of web designers discovers it anew. This separation is what makes our content as backward-compatible as it is forward-compatible (or “future-friendly,” if you prefer). It’s what makes our content as accessible to an ancient device as it will be to an unimagined future one. It’s the key to re-use. The key to accessibility. The key to the new kinds of CMS systems we’re just beginning to dream up.