A close look at the leaves of plants shows that many are covered by waxy, microscopic bumps, or mats of hair. This makes the leaves superhydrophobic. A drop of rain retains an almost spherical shape and runs off easily so the leaf stays dry. Tiny ratchets on butterfly wings direct raindrops away from the insect's body, whether the wing is tilted up or down, and water striders dance on superhydrophobic feet. We are using mathematics, computer simulations and experiments to understand Nature's technology and to design man-made superhydrophobic surfaces, opening up possibilities for applications from low friction microchannels to self-drying fabrics.