Transfected cells expressing fluorescent proteins contain information on the spatial organization of specific target proteins that is accurate at the molecular level. However, conventional optical microscopy is limited by diffraction to imaging on a scale coarser by two orders of magnitude. Together, my colleague Harald Hess and I invented PALM, a microscope which uses the serial photoconversion and localization of hundreds of thousands of individual molecules, including fluorescent proteins or photoswitchable dyes, to build an image at near-molecular resolution. At Janelia, we have each pursued various extensions and applications of this technology, including multicolor and live cell imaging in my lab, and three dimensional interferometric PALM in Harald’s.