White illumination LEDs, with their long lifetimes and energy efficiencies at least 10 times greater than incandescent bulbs, are being massively deployed in illumination applications. Visible light communication (VLC) networks modulate white LEDs at high rates to carry information in a way that is imperceptible to humans. Such communication networks solve the spectrum scarcity problem at RF, are inherently immune to RF interference, and are license-free worldwide. In addition, they inherit the energy efficiency of LED technologies. Indeed, current mobile devices already contain a plethora of optical components, which could be simply modified to be VLC receivers. As many of the 14 billion incandescent bulbs in use worldwide are converted to more energy-efficient LED lighting, a unique opportunity exists to augment them with communications and possible other capabilities.