Fractals have a pattern that we see again after zooming in.

The pattern can be:

• perfectly the same, like the Sierpinski triangle at right, which looks exactly the same when zoomed in by 2

• based on a formula, like the Mandelbrot Set below, which looks a bit different as it is zoomed in

• only general, such as a tree which has a trunk, limbs, branches then twigs

Many things in the real world are like fractals: trees, shorelines, broccoli, lungs, ocean surface, etc.

(Note: the name "fractal" comes from the more technical definition involving "fractional dimensions"!)

See: Mandelbrot Set