Reasons to Validate

Posted by: Josh Walsh in Code.

Validation is the process of ensuring that your web pages (XHTML, XML and CSS files) meet the standard set aside by the w3c, the organization responsible for these markup languages. Validation is similar to running your documents through a spell checker for errors, ensuring that the data sent to the web browsers is well formed and syntactically correct.

Why does it matter?

Web browsers such as Internet Explorer and Mozilla Firefox are responsible for transforming the markup which describes your website into a graphical web page. Writing code which conforms to the w3c’s guidelines will ensure consistent rendering across browsers. Invalid code, even though it may render correctly, is relying on error detection and correction by the browser. In fact, it’s very common for web browsers to render the same page differently, sometimes dramatically.

It’s also important to remember that all web browsers are not the same. Internet Explorer and Mozilla Firefox are today’s mainstream web browsers, but are rarely used by those with visual impairments. Screen reading software, which translates computer content into audio, also reads the markup code. Invalid markup is likely to be read incorrectly, leading to inaccessible websites for many disabled persons.

Content, not Presentation

Despite it’s reputation the past years, HTML and XHTML are used to describe content. The markup language is designed for differentiating types of content (Headlines, paragraphs, lists, tables, etc…), but not for describing how the content should be displayed. You should use HTML to describe your content, and only your content. Allow for presentational markup languages (like CSS) to describe how the content is presented.

By keeping content, presentation and behavior independent from each other you also greatly simplify future maintenance tasks. You can alter existing content and write new content without being burdened with how the content will be displayed and formatted.

It’s the Law

Accessibility is the law in many countries today. You are legally obligated to ensure your websites content is accessible by all.

How To Validate

Checking your website against the w3c’s guidelines is easy. Following the guidelines is not tremendously difficult, although it can require some patience. The w3c has published a free tool for validation, and provides friendly descriptive errors when conditions are not met. You can find this tool at their website.