The Mandelbrot set is, in a sense, a dictionary of all quadratic Julia sets. To see this correspondence, you can click on the image of the Mandelbrot set on the left to pick a complex parameter \(c\) and generate an image of the corresponding Julia set of \(f_c(z)=z^2+c\) on the right. You can then click the Julia set to pick a complex seed \(z_0\) and view its orbit under the iteration of \(f_c\).