The original version was written by Nick Kew of WebÞing Ltd.for their Site Valet service and he has generously donated it for our use.The document has been updated over time, notably thanks to the many Web authors who shared their own rationale and motivation for using Web Quality checking tools.
When surveyed, a large majority of Web professionals will state that validation errors is the first thing they will check whenever they run into a Web styling or scripting bug.
Checking that a page “displays fine” in several contemporary browsers may be a reasonable insurance that the page will “work” today, but it does not guarantee that it will work tomorrow.
In the past, many authors who relied on the quirks of Netscape 1.1 suddenly found their pages appeared totally blank in Netscape 2.0.
Whilst Internet Explorer initially set out to be bug-compatible with Netscape, it too has moved towards standards compliance in later releases.
Here are some reasons they mentioned: While contemporary Web browsers do an increasingly good job of parsing even the worst HTML “tag soup”, some errors are not always caught gracefully.
Very often, different software on different platforms will not handle errors in a similar fashion, making it extremely difficult to apply style or layout consistently.
Using standard, interoperable markup and stylesheets, on the other hand, offers a much greater chance of having one's page handled consistently across platforms and user-agents.
Indeed, most developers creating rich Web applications know that reliable scripting needs the document to be parsed by User-Agents without any unexpected error, and will make sure that their markup and CSS is validated before creating a rich interactive layer.
Validation is one of the simplest ways to check whether a page is built in accordance with Web standards, and provides one of the most reliable guarantee that future Web platforms will handle it as designed.