I’m working with a client at the moment who is using session ids. These have been used for some time to track customers on your website.
Gathering that information is a great way to peer into the mind of your website visitors. The problem is that it can affect your standing in the search engines. And in a big way.
Today, search engines are able, for the most part, to catalog dynamic URLs. Those are the ones that look like this: http://www.YourSite.com/page.html?…. – you’ve seen them all over the Net by now.
With the majority of dynamic URLs, the letters and/or numbers are the same each time for any individual page. The server may grab different content or data, but the dynamic URL remains the same.
But not for session IDs.
Session IDs are used to identify an individual visitor to track them as they move around on the site. That means that the site has a different set of numbers each time attached to the URL.
So, when the search engine spider comes around, it gets the same treatment – a new, individual number assigned to it. But just for that visit.
Time passes and the search engine spider returns. Once again, it calls up a page and, also once again, it is assigned a unique number. A new, unique number different from the last time it came by.
Since the number is attached to the URL, the search engine sees this as a new page. After all, the URL is different than before. Plus, if it tries to call up the old URL (which is the same URL, but the old ID number attached), it gets a 404 File Not Found message.
So, as far as as Google, or Yahoo, or Bing is concerned, there is not static site there. Just a series of brand new URLs being put up constantly.
And if the pages are new, they have no chance to build up in the rankings. That’s a problem.
There is one more thing to consider – search engines, sometimes, still can’t catalog dynamic URLs. Or not 100% of the time at least.
Even Those search engines that can handle them will have problems if there are more than a few characters after the ‘?’. Keep that in mind.
So what can you do to fix this problem? Try using cookies instead of session IDs. Some visitors will refuse the cookie, but that’s worth risking in order to be in the search engines.
Another solution is to fix your site so that session ids are only assigned when a visitor logs in formally – say when making a purchase.
Someone with more programming knowledge than I do might have more solutions to offer so a little searching might be in order.