Phosphors are ubiquitously present in our everyday environment. The most common uses are in fluorescent lamps and display devices; e.g., TV tubes and computer displays. In addition, phosphors are used in medical radiology to transform the x-ray energy to light that is recorded on film for diagnostic purposes. The types of phosphors, mechanisms of operation, and future needs for these major phosphor technologies will be surveyed. In addition, brief mention will be made of some of the minor uses of phosphor materials.