Excessive use of Flash and AJAX technology will cause many problems for search engines. Because search engines cannot index web pages that are entirely represented by Flash or AJAX very well. The reason is simple, search engines only index pages, not applications.
Furthermore, even if a search engine could fully interpret a Flash file or AJAX application and analyze and index their related content, there would still be no way to use URLs to navigate the application. The main purpose of search engines is to submit search results to users, but when processing this media information, search engines will not be able to sort the order of this information. In short, while Flash and AJAX bring more creativity, they also lead to the generation of more spam websites that are difficult to detect.
We are not completely opposed to using Flash and AJAX, there is a way to overcome the above problems. Website designers should only use Flash and AJAX where they are needed. This is the so-called blended approach. Designers should primarily use HTML language to design websites, while using Flash and AJAX as assistive technologies to provide tangible benefits to users. When designing, use as much HTML-based text content as possible.
Usually, a mixture of HTML and JavaScript (DHTML) can basically achieve the effect of using these technologies. For example, clicking a button can show or hide an HTML div unit. This allows a small Flash or AJAX unit to be placed in a traditional HTML layout. In other words, when using Flash and AJAX, you should think of them as units on the page, not the page itself.