Speed Bumps and Walls

Certain types of navigation may block or entirely prevent search engines from reaching your website's content. As search engine spiders crawl the web, they trust on the computer architecture of hyperlinks to find new documents and revisit those that may have changed. In the analogy of speed bumps and walls, complex links and deep site structures with little unique content may serve as "encounters." Data that cannot be accessed by spider able links qualify as "fences."
Possible "Speed Hindrance" for SE Spiders:
• URLs with 2+ dynamic parameters; i.e. http://www.url.com/page.php?id=4&CK=34rr&User=%Tom% (spiders may be reluctant to crawl complex URLs like this because they often result in errors with non-human visitors)
• Pages with more than 100 unique links to other pages on the site (spiders may not follow each one)
• Pages immersed more than 3 clicks/links from the home page of a website (unless there are many other external links pointing to the site, spiders will often ignore deep pages)
• Pages requiring a "Session ID" or Cookie to enable navigation (spiders may not be able to retain these elements as a browser user can)
• Pages that are split into "frames" can hinder crawling and cause confusion about which pages to rank in the results.
Possible "Fences" for SE Spiders:
• Pages approachable only through a select form and submit button
• Pages requiring a drop down menu (HTML attribute) to access them
• Documents accessible only via a search box
• Documents blocked purposefully (via a robots meta tag or robots.txt file)
• Pages requiring a login
• Pages that re-direct before showing content (search engines call this draping or bait-and-switch and may actually ban sites that use this tactic)
The key to ensuring that a site's contents are fully crawl able is to provide direct, HTML links to each page you want the search engine spiders to index. Remember that if a page cannot be accessed from the home page (where most spiders are likely to start their crawl) it is likely that it will not be indexed by the search engines. A sitemap (which is discussed later in this guide) can be of tremendous help for this purpose.