Google says that valid HTML code is a quality signal

Webmasters are not sure about the importance of valid HTML code. Some think that it is very important while other say that it doesn't matter. Last week, Googlesaid that valid HTML code is a quality signal:

"Why does validation matter? There are different perspectives on validation—at Google there are different approaches and priorities too—but the Webmaster Team considers validation a baseline quality attribute. It doesn't guarantee accessibility, performance, or maintainability, but it reduces the number of possible issues that could arise and in many cases indicates appropriate use of technology.

While paying a lot of attention to validation, we've developed a system to use it as a quality metric to measure how we're doing on our own pages. Here's what we do: we give each of our pages a score from 0-10 points, where 0 is worst (pages with 10 or more HTML and CSS validation errors) and 10 is best (0 validation errors). We started doing this more than two years ago, first by taking samples, now monitoring all our pages."

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 relative 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 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 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.

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.