As web sites transition from simple content to full-blown, two-way applications the legacy cruft of the past ten years is becoming apparent. There are millions of sites and billions of pages that have been around since the 1990s. Many of these pages were designed for browsers like Netscape 3, Internet Explorer 2, or even Mosaic. They may have been redesigned several times, but the underlying structure and markup remains the same; and this is becoming a problem. These pages don't work well with modern technologies and tools like AJAX, DOM, E4X, JavaScript, and more.

Consequently, many web developers and designers find themselves faced with legacy code for the first time. Until recently most sites and pages just weren't old enough for legacy issues to be a major concern. While legacy issues and the tools and techniques for managing them are well known to programmers, web folks are just now learning about these problems. As web designers begin to grapple with the legacy issues that have hampered programmers for so long, they'll need to learn the same refactoring techniques programmers have used to manage these problems.