A fractal is a pattern with repeated self-similarity. For this pattern, I cut a square into four smaller squares. I repeated this step in the upper and right three of the squares (see the guide on the left). I repeated this until my pen lines were too thick to go any farther, but a real fractal could repeat infinitely. It has a lacy effect, and actually looks like the famous fractal known as the Sierpinski Triangle (gahh it's everywhere).