Search engine optimization (SEO) is intended to present the best possible image of a site to search engine spiders to ensure the highest possible page rank (PR) on the search engine results pages (SERPs) shown to users who query the search engine. To this end, site designers and SEOs go to great lengths to simplify the infrastructure that forms the underpinnings of a web site. Web sites are constructed using HTML code, a simple computer code that defines how spiders assess a web site for relevance given certain search words, called key words. But SEO involves more than just being recognized by search engines (there are more than 4,000 of them currently operating on the W3, by the way). It's just as important that an optimized site be completely and accurately indexed by search engines. If a site is mis-indexed or partially indexed, it won't appear on the SERPs regardless of how well the infrastructure behind the site is optimized.

What is Site Navigation? Site navigation is made up of all of the "road signs" used within a web site to assist visitors in finding the information they're looking for. Elements of site navigation include things like navigation bars, buttons, embedded text links, tabs and other "click on" devices used by visitors to navigate through the different pages of a web site. Now, given that SEO is intended to optimize a site for search engine spiders and site navigation is intended to help humans find their way around, it might seem somewhat incongruous that SEO and site navigation have much in common.

However, they are most certainly connected. Site Navigation and SEO To put it bluntly, search engine spiders are dumber than a bucket of mud. They don't think, they're unable to place site content within any context and they lack the ability to determine narrowly-defined site purposes and functions. In fact, even with the complex algorithms (mathematical formulae) employed by today's search engines, it still comes down to key word selection, key word density and key word placement within the HTML coding when it comes to indexing a site. A site with the key words "pet, pet supplies, pet food, dogs, cats, fish" and other similar key words will be indexed as a pet store or pet supply company and, as such, will appear on the SERPs when a user enters the key words "pet supplies," etc.

A site owner who chooses inaccurate key words pays a price in the lack of search engine-driven traffic, as in fewer visitors. So, how can you be assured that your site is completely and accurately indexed? Spiders Follow Links Just like human visitors, search engine spiders follow links within a web site. So, a link off the menu bar to the About Us page will be followed by both humans and search engine spiders. And the more links on the site, the more completely and accurately the site will be indexed. So, if a site's navigation links are easy to follow for humans, they'll be easier to follow by search engine spiders.

Links direct humans and spiders whenever they visit a site. Gray and Black Hat Tactics Black hats (from the old movie westerns in which good guys wore white hats and bad guys wore black hats) are site designers, developers and owners who employ tactics that are intended to diminish the reliability of SERPs, i.e., to fool search engine spiders.

How? Well, how about placing invisible text on a site's something frowned on by search engines. If a black hat places white text against a white background, it is invisible to human eyeballs but is easily seen and scanned by spiders. So, an unscrupulous owner can load up a site with keyword dense, invisible text hoping that spiders will get the picture. Similar to invisible text is invisible links - links that can be seen by spiders but not by humans. This falls into the "gray hat" category and it works like this: we've all come to expect text links to appear in a different color from the rest of the site text.

The ubiquitous blue text usually identifies to visitors a link to another page within the site or to another site altogether. We've all seen these text links and clicked on them to navigate our way through a web site. But what if that blue text link wasn't blue at all? What if it was the same color as the surrounding text? Spiders would follow the links but humans wouldn't be aware of them because they'd blend in with the rest of the site content. Harmful? Not really. Intended to fool spiders? No. Invisible links are intended to keep spiders on site for as long as possible.

The longer a spider stays on a site, the more pages of that site will be indexed in the search engine. Site owners want to keep spiders around as long as possible to ensure the most complete indexing. Gray-barred When black or gray hat tactics are detected by spiders, a site may be penalized in page rank, may only be partially indexed or may be gray-barred - the term used when a site is dropped from a search engine entirely. When a site is gray-barred, it's essentially invisible to visitors. The site owner may as well put up the "Going Out of Business" sign because s/he is going to do just that - go out of business. The Road Map to Successful SEO Design your site's navigation for humans.

Keep it simple and keep it honest. For example, if a navigation tab is labeled "Products" but it takes visitors to a page full of sales hype, you'll lose points with the search engine based on the correct assumption that you're trying to fool the visitor and the spider. Employ lots of text links, visible to humans and spiders. Again, spiders follow links.

They keep the spider on site, indexing more pages. That's a good thing. Keep links clearly and properly labeled. A mis-direct may get you in trouble with Google. It may also get you gray-barred and looking for a new line of work.

In a nutshell, if your site's navigation is simple, clear and straightforward, you visitors will appreciate the simplicity with which they find desired information and search engine spiders will smile kindly on your site by indexing it accurately and completely.

Radin Yousefi is the CEO of Pluginlab.com. A software company creating some of the most popular tools for web site designers and developers. To learn more, visit www.pluginlab.com