Publisher Summary This chapter deals with fundamentals, techniques, and applications of atmospheric ultraviolet remote sensing. Fundamentals include the relevant physics and chemistry of the atmosphere, which is sometimes called “aeronomy.” The emphasis is on passive sensing of the Earth's atmosphere from space, but the atmospheric properties and experimental techniques discussed are important for active methods, such as lidar, as well. Passive methods involve use of naturally occurring emission from airglow, aurora, and scattering. In addition, passive sensing includes the occultation of UV sources, such as the sun by photoabsorption in the atmosphere, and the use of solar flux measurements in global atmospheric models. The relationships of ultraviolet to infrared, visible, and x-ray methods are pointed out. The altitude range covered extends from ground level to the magnetosphere, with most of the emphasis from the stratosphere through the thermosphere.