Consistency in experimental observations, numerical calculations, and theoretical predictions have revealed that the skins of water and ice share the same attribute of supersolidity characterized by an identical H-O vibration frequency of 3450 cm(-1). Molecular undercoordination and inter-electron-pair repulsion shortens the H-O bond and lengthens the O:H nonbond, leading to a dual process of nonbonding electron polarization. This relaxation-polarization process enhances the dipole moment, elasticity, viscosity, and thermal stability of these skins with a 25% density loss, which is responsible for the hydrophobicity and toughness of the water skin and results in the slippery behavior of ice.