“Fractal” may seem a bit odd (especially since Jay has written about fractals in the strict mathematical sense in another book). In this case, though, we’re using the term somewhat metaphorically. By strict mathematical definition, a fractal is a geometric shape that has symmetry of scale, meaning that you can zoom in to an arbitrary depth and see the same pattern repeated. Figure 10-1 shows a fractal tree that Jay created by writing a Java class. It represents our notion of building many pages from a few reusable components.