Fluorescence microscopy is one of the most powerful and widely used imaging techniques in biological research because it can visualize dynamic processes inside living cells with exquisite sensitivity and specificity. Major breakthroughs have included the development of confocal microscopy in the 1980s and two-photon microscopy in the 1990s. These advances have been accompanied by groundbreaking improvements in the ability to visualize specific proteins and organelles inside living cells using fluorescent proteins (for example, green fluorescent protein (GFP)) and transgenic technology. In addition, tremendous increases in computing power have enabled the acquisition and analysis of large imaging data sets and thus have further facilitated the ascendancy of fluorescence microscopy.