There are common web design techniques that inhibit search engine spiders from properly indexing web pages. You don't have to avoid using these techniques altogether, but you should avoid using them in situations where they obscure links and ASCII text from search engine spiders. There is no single set of standards or specifications for SEO. Search engine companies also capriciously change their techniques for compiling search results. The concepts mentioned here, however, are a good set of suggestions for you to consider as you develop your own best practice policies.
Since most webbots and spiders lack JavaScript interpreters, there is no guarantee that a spider will understand hyper-references made with JavaScript. For example, the second hyper-reference in Listing 26-6 stands a far better chance of being indexed by a spider than the first one.
<-- Example of a non-optimized hyper-reference -->
<script>
function linkToPage(url)
{
document.location=url;
}
</script>
<-- Example of an easy-to-index hyper-reference -->
<a href="http://www.MySpace.com/haxtor">My home page</a>
Listing 26-6: JavaScript links are hard for search spiders to interpret.
Search engine spiders depend on ASCII characters to identify what's on a web page. For that reason, you should avoid presenting text in images or Flash movies. It is particularly important not to design your website's navigation scheme in Flash, because it will not be visible outside of the Flash movie, and it will be completely hidden from search pages. Not only will your Flash pages fail to show up in search results, but other pages will also not be able to deep link directly to the pages within Flash movies. In short, websites done entirely in Flash kill any and all attempts at SEO and will receive less traffic than properly formatted HTML websites.