On 16 May 1960 Theodore Maiman operated the first laser using a ruby crystal illuminated by a flash lamp. The result was coherent, monochromatic, and intensely directional light — properties no prior light source possessed. The laser turns light from phenomenon into tool: surgery, metrology, fiber-optic communications, data reading, industrial manufacturing, spectroscopy, and confocal microscopy are all direct applications. In the genealogy of optics, the laser is the point where the wave physics of Fresnel and Maxwell materializes into an instrument that redefines what light can do.