Is your HTML code valid for the SE?

You have placed your most important keywords in your web page title. You have the optimal keyword density on your web page. Your link popularity score is shooting through the roof. You have added lots of content to your web site. You have double-checked your robots.txt file. You have read the past 70 newsletter issues and you're becoming the status of an search engine optimization expert in your company. :)

In spite of everything - your web site is still ranked nowhere at all. Then it comes to your mind... are the search engines actually able to read my web pages at all?

Web pages are written in a special language called HTML. Like any language, HTML is constantly changing although there's the World Wide Web Consortium (W3C, for short) which is the governing body that establishes what is valid HTML
code and what is not.

Search engine crawler programs obey the HTML standard. They are only able to index your web site if it is compliant to the HTML standard. If there's a mistake in your web page code, they stop crawling your web site and probably forget what they've collected so far.

Fortunately, the W3C offers a free online service that can check the HTML validity of your web pages. You can find it here.

Another benefit of writing clean HTML standard compatible code is what the W3C calls "interoperability". It means that valid code is automatically cross-browser compatible, i.e. it works in different web browsers on different operating systems (although the actual display of the HTML code depends on the web browser).

To help search engine crawler programs to index your web site, you should also follow these tips:

Use simple tables in your HTML code and avoid overly nested tables, i.e. tables within tables within tables. Most HTML errors can probably be found in this area.
Move long JavaScript code to an external .js file. Search engines cannot read JavaScript code..
Use Cascading Style Sheets (CSS) to remove excessive usage of HTML font tags. Replacing font tags throughout a page with styles saves a significant amount of code and makes it easier for search engines to index your web page.

If you use Cascading Style Sheets to make your web pages smaller, make sure that they are also technically correct. Fortunately, the W3C also offers a free CSS validation service.