1. What Flash Can Do

You can use Flash to create animation, graphics, interactive sites, and entire applications for the World Wide Web. Flash reduces download time dramatically by using vector animation, a frame interpolation method called tweening, and reusable elements known as symbols.

There is one catch—users must have the Flash Player plug-in installed on their browsers to view Flash web pages. However, Flash comes preinstalled on most recent computers and browsers. An NPD Research study funded by Macromedia estimates that 97.4% of 397 million Web users can view Flash content without having to download a plug-in.

But even 2.6% of users add up to more than 10 million people who can't see Flash without downloading additional software! That's why it's a nice courtesy to notify users when a site requires Flash and include a link to download the player from Macromedia.