Many webmasters overlook a very important aspect of website promotion: the validity of the HTML code.

What is valid HTML code?

Most web pages are written in HTML. As for every language, HTML has its own grammar, vocabulary and syntax, and every document written in HTML is supposed to follow these rules.

Like any language, HTML is constantly changing. As HTML has become a relatively complex language, it’s very easy to make mistakes. HTML code that is not following the official rules is called invalid HTML code.

Why is valid HTML code important?

Search engines have to parse the HTML code of your website to find the relevant content. If your HTML code contains errors, search engines might not be able to find everything on the page.

Search engine crawler programs obey the HTML standard. They can only index your website if it is compliant with the HTML standard. If there’s a mistake in your web page code, they might stop crawling your website and they might lose what they’ve collected so far because of the error.

Although most major search engines can deal with minor errors in HTML code, a single missing bracket in your HTML code can be the reason if your web page cannot be found in search engines.

If you don’t close some tags properly, or if some important tags are missing, search engines might ignore the complete content of that page.