Why XHTML and CSS Compliant?
Have you ever gone to a page on the Internet that says “This site requires Microsoft® Internet Explorer 5.0 or higher”? This is not the way the World Wide Web was envisioned, many years ago. The World Wide Web Consortium (W3C) is the organization responsible for developing the languages used to define pages on the World Wide Web. Over the past 15 years, these standards have evolved to cover a wide range of content presentation options. Far from the simple underlining and bolding of early web pages, pages now have other formatting options, such as highlighting when you hover your mouse over text, TLAs (put your mouse over that for a few seconds), and other interesting transformations. The W3C isn’t responsible for some of the “richer” content, such as Java applets, Flash animations, or streaming media (although they are responsible for defining the rules of how web pages identify such content to the browser).
To facilitate web pages that are viewable by the largest number of people, from every geographic region in the world, using a large number of different operating systems and devices, the W3C has established standards. The HTML standards define the way a page should be built. Without going too deep into the weeds, imagine a rough draft of a paper you did in school. As you refined it, you marked it up — you underlined a passage here, circled one there, crossed a phrase out, made a note in the margin, etc. (Hopefully, when you got it back, the teacher hadn’t “marked it up” too much!) This is what the “markup” in HTML means. If you want to highlight text on a regular piece of paper, you put the pen on the paper at the start of it, and you drag it across the text until you come to the end of the text you want to highlight, at which point you stop. In HTML, you put a starting “tag” at the starting place of the text, and an ending “tag” at the end – this way, the browser knows how to transform the text in the middle.
The XHTML standard brings HTML into the 21st century, by refining the way web pages may be constructed. In XHTML, for example, every start tag has to have an end tag, even if common sense would tell you that the previous one should be closed — you can’t have a paragraph within a paragraph, but you still have to close the previous one before starting a new one. It also defines a set of ways to manipulate text on a web page, using techniques that encourage designs that will look the same no matter what browser is used to view it. CSS provides the means of defining a common style, and of pulling that style outside of the page, so it can be reused across multiple pages, even throughout entire websites.
The bottom line — This is why XHTML and CSS compliance is important! Building pages to these standards is the least a web developer can do to make sure that his website is accessible by the largest number of people. Compliance with a standard also establishes a fixed reference for changes to websites — even if the XHTML 2.0 standard comes out and completely changes everything, XHTML 1.0-compliant pages will not change, because the browsers won’t try to format them according to the XHTML 2.0 rules. In business applications especially (and personal endeavors, too), continuity is very important — the image you present to your customer (or potential customer) makes a first impression, and it’s important that this impression is a good one!
What can you do? If you’re not a web developer, you can still check for compliance. The W3C has an HTML Validator and a CSS Validator that you can give a URL, and it will validate the page for you. At the bottom of each page from DJS Consulting, you’ll find a link that validates that page for you, without having to type it in or cut-and-paste. Additionally, if you run Mozilla Firefox (which I personally encourage), there are several extensions that will validate the web page you bring up in your browser. They work quite well, and it’s quite enlightening to turn that on and go surfing. You’ll find very few pages that are compliant (although running an ad-blocker can cause this, as it causes pieces of web pages to not be loaded). Again, if you’re not a developer, there’s not much you can do to change whether web pages are built correctly or not — but, you may find it interesting to be aware.
If you are a developer, pick a standard (XHTML 1.0 Strict may be a lofty goal if you’re just getting started, but there are other standards that are a little less “strict”), validate against it, and make sure that the pages you build are truly interoperable.