Fractal: “A rough or fragmented geometric shape that can be subdivided in parts, each of which is, at least approximately, a reduced size copy of the whole.” (Benoit B. Mandelbrot)

In short : A fractal is a never-ending pattern. It has no whole or end, meaning you can zoom in and find the same shapes forever.

Far from being only a mathematical curiosity, this zoom symmetry can be found everywhere in nature (e.g. fractal samples images below). Indeed, fractals are exquisite structures produced by nature, hiding in plain sight all around us.

Although fractals are very complex, they are made by repeating an amazingly simple process. This gives us here a perfect subject to play with recursion, it is a great module to experiment, explore, and make our creations.

To appreciate the beauty of fractality.
To feel recursivity.
To explore.
To create online our fractal.

#### What else?

The primary practiced technique here is about recursions : the repeated application of rules to successive results. Indeed, each new level of details in a fractal is a recursion of the first pattern. We will also deal with String Rewriting Systems.