Why are Flash sites a brick wall to search engines?

That nifty Flash site of yours isn't as nifty as you think. While Flash is great for certain tasks like presentations and multimedia, the truth of the matter is that a Flash website simply is a movie

file that is stuck in an HTML file. And that presents a big problem, because technically speaking; minus the HTML to load the Flash movie; you have absolutely nothing on your page that a search engine could find should it decide to crawl through your site. It is essentially the same thing as if NOTHING was there at all. This may be stating the obvious to most people with any HTML under their belt; but that does not seem to curtail the number of Flash based sites that I see on a daily basis all over the internet. There are a few solutions that can help a Flash site to garner more traffic; and I will explain them in a second but I wanted to really stress that absolutely none of these solutions is really a good substitute for having crawl friendly pages. Take into account as well that many of the effects that are achieved using Flash can be replicated using JavaScript libraries like jQuery, Mootools; Spry, Scriptaculous, and so on. When I was webmastering Karkula.com I was deeply troubled because the database programmer who rendered the site prior to my coming on board decided to call the database from FIleMaker using Flash. We had to arrive at a solution of "deep linking" which is a process that essentially assigns a URL to an item inside of a Flash movie; generally speaking content from a database of some sort is required to achieve this. A second workaround that was developed was HTML mirroring of content rendered by the Flash movie; so essentially we output the same words for the items that appeared in the Flash movie, underneath the Flash movie so that the items could be indexed properly. To date this is the best solution that I have been involved with in terms of trying to make Flash SEO-Friendly but again I stress; it is not nearly as good a method as simply generating the content via standard HTML to begin with. An example of how the body structure on a Flash movie ONLY based site looks like the code in the example box. As you can see, the only content in the page is an embed tag for the SWF movie. But Google DOES index SWF files.... Yes, that is correct, Google does and can index content that is in SWF files. Actually, Yahoo is now in the act as well, thanks to pressure from Adobe after it's purchase of Macromedia. But the fact remains that there are many, many other search engines on the web that do not read SWFs at all. I will openly say that the no-Flash indexing is slowly becoming a thing of the past; but there are a lot of different variables that will affect the SEO-optimization of a Flash site; for instance the version of Flash that the site was made with, or is compiled for; and the inclusion of helper HTML to aid the Flash as well. For more information, I suggest you start here at Adobe's Developer Center.