Dynamic pages are roadblocks to high search engine positioning. Especially those that end in "?" or "&". In a dynamic site, variables are passed to the URL and the page is generated dynamically, often from information stored in a database as is the case with many e-commerce sites. Normal .html pages are static - they are hard-coded, their information does not change, and there are no "?" or "&" characters in the URL.

Pages with dynamic URLs are present in several engines, notably Google and AltaVista, even though publicly AltaVista claims their spider does not crawl dynamic URLs. To a spider a "?" represents a sea of endless possibilities - some pages can automatically generate a potentially massive number of URLs, trapping the spider in a virtually infinite loop.

As a general rule, search engines will not properly index documents that:

• contain a "?" or "&"
• End in the following document types: .cfm, .asp, .shtml, .php, .stm, .jsp, .cgi, .pl
• Could potentially generate a large number of URLs.

To avoid complications, consider creating static pages whenever possible, perhaps using the database to update the pages, not to generate them on the fly.