How to avoid confusing indexing-spiders with your site's session IDs and cookies.

• My ecommerce site uses cookies to track which items my customers place in their shopping carts. If the customer has cookies disabled, then my site is set up to track them using session IDs in the URL.

  The problem is, I've heard that search engine spiders don't like cookies or session IDs. Is there any way to track both my customers' shopping carts and make my site search engine friendly?

Answer: Search engine spiders don't accept cookies, so cookies don't have any affect on your rankings. The search spiders simply never see them. However, if your site requires that users accept cookies in order to use the site, that will create problems because spiders can't accept cookies.

Usually, if a user rejects cookies (such as a search spider will, or a user with a browser which has cookies turned off will) then most ecommerce programs are set up to track that user using URL-based session tracking IDs. That means they add a unique identifier like ?sid=jdf47hw3ih9023kjefn2k to the URL of every page the user visits. This enables tracking the visitor, the items they have in their shopping cart, and so forth.

However, this creates a problem with search engine indexibility since spiders prefer not to index pages that have session IDs in the URL. Session IDs are notorious for trapping a spider in a loop (they call that a spider trap) where the same page gets served to the spider over and over—each time with a different session ID.

In other words, each time a search engine downloads the page, it sees a different session ID tagged onto that page's URL. This can confuse the search engine into thinking that it's a different page, rather than the same page but with a URL based on the different session ID number.

In most cases, search engines simply won't index URLs that have anything that looks like a session ID. They use this as a self-protective measure to avoid filling up their index with identical pages....