A List Apart: Frameworks for Designers

"These days, “framework” is quite a buzzword in web development. With JavaScript frameworks like the Yahoo User Interface library, jQuery, and Prototype getting a lot of attention and web application frameworks like Rails and Django getting even more, it seems like everyone is using some kind of framework to build their sites. But what exactly is a framework? And are they only useful to programmers, or can we web designers benefit from the concept, as well?"

http://www.alistapart.com/articles/frameworksfordesigners