Flash, by Macromedia is an easy way to create interactivity and animation to your Web environment. File size is surprisingly small and works across many browsers. Flash can now be combined with RealMedia to create real time full animation . Needs Shockwave plug-in . Can perform using Java Player but much more limited.
Graphics are mostly vector images to reduce file size which can be restrictive.
Quality is out performing competitors at this stage. Free plug-in widely distributed. RealMedia Plug-in required. Proprietary software server also needed to take advantage of streaming. Panning motion tends to be pixilated.