A fractal is a form with parts , duly amplified,  resemble the whole. The same thing occurs with the parts with regard to their own parts. And so on, and on and on . It is perhaps the simplest way of creating complexity; repeating a pattern a given numberof times in ever smallet scenarios. Ligthining is fractal , as are frens, trees, minerals as such as pyrolusite... Plants are usually fractal outside, while the animals are fractal inside: nervous system, circulatory system respiratory system.... Fractals are good way of reaching large number of points in space with certain continuity.