Flash is a vector animation software. Today it is used for many things such as intro's to websites, buttons on websites, videos and banners.

Many Web Developers prefer Flash because it is virtually limitless to what you can create.

Many companies choose Flash because it gives the viewer an extrememly rich viewing experience they would not get using simple HTML/CSS/Javascript.

Flash is widely used around the world, currently 97% of computers have some version of Flash installed.