As developers of the technology state, Flash is the current industry standard for interactive vector graphics and animation on the web.

Interactivity means that a visitor can click on elements of a movie, and the movie will respond accordingly if programmed to do so. It is possible to build the entire site using nothing but Flash.

Vector graphics has a number of advantages comparing to raster: it has a much smaller size, and its size in bytes does not depend on the size of movie in pixels. You can resize movie window in course of playback and this will not result in quality loss as it would with raster animation or video.

However, the price for this is that your visitor has to have corresponding software. Special program called Flash Player transforms the data from .SWF file into graphic output in your browser. Luckily, Flash has been around for long enough to be widely supported. The newest versions of browsers have a built-in Flash Player. If not, the player may be provided by the operating system. Around 90% of computers do display flash content. But even if you are unlucky and don't have the player there is still a way out. Flash animation should be embedded into HTML in such a manner that in case client's browser does not have playback capability it is automatically redirected to Macromedia site for downloading the program (for free, of course). The size of file is comparable to that of an averagely sized movie. When download completes the newly obtained player is put to work smoothly, so that the person using the browser does not even feel the difference. Well, at least, that's the theory :-).