Many web pages nowadays are embellished with Flash animation products, offered by Adobe. Flash technology allows, in a very simple manner, to insert small animated, vector-based drawings into your web pages.
Of course, these animations have some influence on the way your site is "seen" and indexed by the search engines. The problem of Flash Search Engine Optimization arises, which is a very serious matter in terms of conversion and web site profitability.
What Are Flash Animations?
When you create an animation, you get a file, named, for example, banner.fla. The ".fla" represents the Flash format extension. In order to display this file in a web page, you need to export it in Shockwave Format (extension .swf). It is this file, once exported, that you will be using for your web site.
Any text that you include in the animation probably won't be indexed by the search engine as they rarely give attention to these formats. In spite of this there are search engines (Google, dir.com etc) that are able to read the text in these Flash components. The result is that any site or webpage that is built entirely in Flash will be invisible to the search engines which index only text content in html format.
Why Use Flash for Sites?
Due to the limited content contained on sites built entirely in Flash search engines will have difficulty indexing them and will therefore avoid these sites. Additionally spiders are not abIe to read the content of a .swf file. Some webmasters use flash to build mini-sties for specific campaign sites.
Here are a couple of reasons people find Flash worth the effort.
The impact of animation is maximized with flash and this improves the web's interactive and visual environment.
It can be combined successfully with other technologies (e.g. PHP, MySQL, XML, images, video, sound, etc.). It is therefore perfectly possible to create a dynamic web site in flash that also has content.
Pros

It allows the designer to put more content in a small-sized space without damaging the layout.
It is an easier way to present slide shows or Flash components.
It is a great tool to create banners and ads, and even Flash videos.
It's a good instrument for creating great visual impact and drawing attention to specific points of interest on a web site.
Cons
Sites utilizing flash could take some time to load and it increases bandwidth consumption.
The vast majority of search engines will not index sites built entirely with Flash.
You could be at the mercy of the Flash developers - if you use 3rd party Flash developers, they might code the project so that you won't be able to make any changes and you will have to pay them for modifications
The "Back" button is usually disabled for flash websites and also Google's AdWords won't approve pages that have the Back button disabled. So, beware of this if you intend to promote your web site by using a PPC campaign.
Flash may interrupt the visitor's experience on the site. For instance, never ending movies and sounds without volume control may drive some site visitors away.
Splash Pages will reduce your visibility in the search engines especially if there is insufficient text on the site that can be used to identify the keywords associated with your products and services.
It is not an easy task to optimize flash for the unpredictable search engines. The amount of time and energy it takes for SEO for Flash websites is far greater than the efforts required for an HTML site.