Why use XHTML DOCTYPE Declarations?
In the early days of the Web (late 90’s, early 2000’s), each Web browser had its own way of interpreting HTML and CSS. Web designers often resorted to complicated workarounds (essentially hacks) that depended on a browser’s buggy behavior in order to create a desired effect on a Web page. These days, as Web standards and browsers have become more mature, most Web browsers fully support the XHTML standard, and designers no longer need to rely on these workarounds, rather they can create new Web pages which only use XHTML compliant syntax and expect a certain level of browser compatibility. But what about the billions of existing pages which were designed for misbehaving browsers? If they were to properly render pages according to the standards, they would ruin their bug-dependent design. Thus, Microsoft Internet Explorer and Netscape 6 revert to their old “quirky” (i.e. busted) way of rendering pages, unless they adhere to the XHTML or HTML 4 standards — and the way to tell the browser
