Both the Mandelbrot & the Julia sets are generated by computing z*z+c and feeding back the result as the next value of z. z & c are so-called ‘complex numbers’, which aren’t complicated at all. It simply means that they are composed of 2 parts, ‘real’ and ‘imaginary’, like so: z=x+iy, where i*i=-1. The feedback loop is stopped either when z exceeds some value, or the loop has repeated more than some number of times. Which one happens determines if the point being tested is inside or outside the set. If outside, the size of z may be used to pick a colour for the point. Infinite complexity from a few lines of code - how amazing is that?