The deferment of presentational details until the last stages means that a document can be easily re-purposed for an entirely different medium, with merely the application of a new stylesheet prepared for the new medium and consistent with elemental or structural vocabulary of the semantic document.

A carefully authored document for a web page can easily be printed to a hard-bound volume complete with headers and footers, page numbers and a generated table of contents simply by applying a new stylesheet.

Source: Wikipedia