There is a definitive set of rules and guidelines that should be followed with writing HTML. HTML validation is the process whereby a HTML document is analysed to see if it sticks to official HMTL rules and guidelines. By using HTML validation, errors are fixed and weeded out, resulting in a site which is clean and compliant, with a professional look.

There are multiple reasons to produce valid HTML and XHTML codes, such as the following:

Website accessibility – by validating your html code, you can pinpoint errors that could prevent search engine spiders, and users from accessing your page.  Doing so allows your site to be viewed by wider range of devices, such as screen readers, text browsers and search engines. This in turn will enable your site to be more accessible to a larger audience, such as those who are vision impaired, cognitive impaired, and motor skill impaired.

Search engine friendly – having a simple and clean code will enable search engine robots to crawl through your webpages quickly and completely.

Faster loading – if there are many errors in your HTML code, then it will take longer loading time for search engine robots to browse through it. A page is deemed pointless if it takes too long to load, therefore slow loading time could result in your web page losing visitors.

Easier to maintain and update – your website will be easier to maintain and update once your initial code is clean and structured.

Compatible with all browsers – having validated code ensures that your page will perform correctly in all browsers.

Getting wider scope – once a website is visible in all browsers, and is indexed properly by all search engines, then it will get a wider scope in terms of visitors.