Many web designers make the mistake of designing their documents for specific screen resolutions. When the document is displayed on a smaller resolution the page elements tend to jam together or break across unexpected lines.
Your documents should be suitable for many resolutions. Although most users will be running at resolutions of at least 800×600 pixels, your websites may have the occasional user running lower resolutions or too high resolution. Therefore, it`s advised and is an industry standard to always test your documents at various locations & colour depths to look for many shortcomings.
Validating your document`s code is another very good idea. It helps double check your document for simple errors – typos, unclosed tags & so on – and also verifies that your code meets expected standards.
There are many ways to validate your documents, but they all rely on your documents containing a correct document type definition (DTD) declaration. For example, if you want to base your documents on Strict HTML 4.01, you would include the DTD declaration at the top of your docuemnt within angular brackets.
The DOCTYPE declaration informs any user agent reading the document what standard the document is based on. The information is primarily used by validation clients in validating the code within the document, but it might also be used by a display agent to determine what features it must support. Some of the tools/resources where the code can be validated are:
1. The online W3C HTML validation tool
2. The online Web Design Group (WDG) validation tool
3. Validation utilities built in to Web development tools such as Adobe`s Dreamweaver.
4. Any of the various separate applications that can be run locally. A comprehensive list is maintained on the WDG site.
5. The online CSS validation tool
Many a times, the document may look like conforming to HTML but the validators think otherwise. Some of the points that should be kept in mind before the validation takes place are like that the [input] element must be contained within a block element other than the [form] tag. Typically, the paragraph tag [p] is used but you can also use [div], a heading, [pre] and so on.