Fractals are both geometric forms found in nature and mathematical constructs. As geometric forms fractals are characterised by scale invariance, meaning similar patterns repeat themselves at various scales of magnitude. Scale invariance means that fractal structures have a symmetry with respect to scale, meaning the scale can change but the structure will repeat itself over various levels of magnitude. Many systems are found to exhibit this fractal property such as snowflakes, rivers, mountain ranges and coast lines. As mathematical constructs fractals are found to derive from iterative functions, the most famous fractal called the Mandelbrot set – so named after the discover of the concept of fractals – is a product of a simple iterative map over complex numbers. Fractals are of particular relevance in the field of chaos theory as the graphs of most chaotic processes are fractal.