Adobe Macromedia Flash is based on 'vector' graphics. Instead of having to retrieve every individual pixel in an image, as you do with the bitmaps used in GIFs and JPEGs, vectors describe shapes as a set of coordinates. For a simple rectangle, for instance, you only need the coordinates of two opposite corners - just four numbers, and maybe a few more to provide the fill and border colors. So, file sizes are very small indeed.
Flash is not a good choice for photographic images but is ideal for 'line and fill' type images - although it can cope with simple blends. You can create simple drawings in Flash, but it is much better to do them in a more powerful drawing program like FreeHand or Illustrator and import them.
Apart from having small file sizes, Flash animations are scaleable - you can zoom in and out without any loss of quality. As it anti-aliases on the fly, drawings and type are beautifully smooth at any size.
Flash doesn't allow as much interactive control as Director Shockwave but probably enough for most Web purposes. The Flash plug-in already is one of the most popular downloads on the Web and is expected to be bundled with future version of Netscape.
This prize-winning Flash example by The Freddie Street Cats is a mixture of traditional animation and interactivity.
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