Photoemission is a process in which electrons are emitted from a material when it absorbs light or electromagnetic radiation. This phenomenon occurs when photons, which are particles of light, strike the surface of a material and transfer their energy to electrons. If the energy of the photons is sufficient, it can overcome the binding energy of the electrons, allowing them to escape from the material. This effect is commonly observed in metals and semiconductors and is the basis for techniques like photoelectron spectroscopy. Photoemission plays a crucial role in various applications, including solar cells and cathode ray tubes, where the control of electron emission is essential for device functionality.