How important is validation?
Many people are not aware of the importance of validation. Many see it leading to unnecessary problems that cannot be easily fixed or unwanted work arounds are needed to achieve the same overall layout. But is validation necessary?
Well, Validation makes many website designers aware whether their pages are up to correct standards as they show what tags are unacceptable as well as helping the designer to spot mistakes which could affect the browsers rendition of the page.
Also this could become a problem to those who use accessibility tools as they many not be able to view the website properly.
Additionally by validating your code you are making sure that your markup is more likely to be more compliant with future technologies as when newer standards are introduced less time would be spent adjusting what you currently have, whereas it would be more difficult to introduce a compliant website and all of the unnecessary waste of time could be avoided if standards was introduced in the beginning.
But who controls the standards? Well, the W3C lays out the rules and tags required for each standard, so, it may be useful to look at the recommendations that W3C lays out on their website (www.w3c.org)
So the main question is; How do you check that your markup complies to each standards?
Well, the W3C has many automated validators where code can be checked and errors or warnings can be shown for instances where they do not comply to the standards as well as possible solutions to fix these problems.
However there are also many other ways which you can check the status of your website. For example you may not know that many programs also contain a validator, such as Dreamweaver and that there are various firefox extensions available which can also validate your page.
The most important extension that I recommend is the web developer toolbar which also features a validator (https://addons.mozilla.org/en-US/firefox/addon/60).
Additionally validators do not just restrict one particular markup as they are available for nearly all major languages such as CSS and XHTML.
Validators can also be used to check the existence of links within a file such as broken links.
However do be aware that not all validators can check that the page conforms to all of the necessary standards as many have limitations but the chance that this is the case is very limited.
Essential Links
http://validator.w3.org/
http://validator.w3.org/checklink
http://jigsaw.w3.org/css-validator/
http://feedvalidator.org
