Fractal geometry is the mathematics of roughness: how to reduce the outline of a jagged leaf, a rocky coastline or a static in a computer connection to a few simple mathematical properties - to make the complex simple. With his fractal tools, Benoit Mandelbrot has got to the bottom of how financial markets really work. He finds they have a shifting sense of time, a unique dimension and a wild kind of behaviour that makes them volatile, dangerous - and also beautiful. In Mandelbrot"s fractal models, the complex gyrations of IBM"s stock price, the FTSE 100 cotton trading and exchange rates can be reduced to straightforward formulae that yield a much more accurate description of the risks involved.