Small bubbles of gas are known to exist at the interface between hydrophobic solids and water. Two features of these bubbles are unexplained: the very low contact angle and the stability. A self-consistent explanation of both of these effects is that there is a film of contaminant at the air-water interface that decreases the surface tension and thus the contact angle, and also hinders diffusion of gases from the bubble, thereby increasing the lifetime. If, during the lifetime of the bubble, the surface tension increases faster than the area of the air-water decreases, the interfacial energy can lead to a stabilization of the bubbles.