Why valid HTML code is crucial to your web site's search engine optimization efforts and subsequent high rankings:
Many webmasters and newcomers to web page design overlook a crucial aspect of web site promotion: validity of 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 each document written in HTML is supposed to follow these rules.
Like any language, HTML constantly changes. As HTML has become a relative complex language, it's very easy to make mistakes ... and we do know by now favorable weight new msn.com beta search engine places on proper coding practise ... see a recent article on msn.com coding requirements
HTML code that is not following official rules is called invalid HTML code. Why is valid HTML code important to search engine optimization and your whole marketing effort?
Search engines have to parse HTML code of your web site to find relevant content. If your HTML code contains errors, search engines might not be able to find content on page, and there ends your seo efforts and quest for high rankings of that page.
Search engine crawler programs obey HTML standards. They only can index your web site if it is compliant to 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 error.
Although most major search engines can deal with minor errors in HTML code, a single missing bracket in your HTML code can be reason your web page cannot be found in search engines.