Google says that valid HTML code is a quality signal

Here is an exerpt from a good article with a link to a helpful tool:…

“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….

Why is valid HTML code important?
Search engines have to parse the HTML code of your web site 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 web site if it is compliant to the HTML standard. If there’s a mistake in your web page code, they might stop crawling your web site…

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.

How can you check the validity of your HTML code?
Download IBP and select the HTML validator in the “Tools” menu. Enter the address of a web page and you will see how many errors the page contains.  Although not all HTML errors will cause problems for your search engine rankings, some of them can keep web spiders from indexing your web pages.

Valid HTML code makes it easier for search engine spiders to index your site. Checking the HTML code of your web pages only takes a few minutes but it will have a major impact on the accessibility of your web pages.”