This document discusses the Compton effect, which was discovered in 1923 by Arthur Compton through an experiment where he directed x-rays at a carbon target. The x-rays were scattered in different directions. Compton's discovery showed that photons have momentum and energy, and that photons lose energy and momentum after colliding with electrons. This effect can be quantified using the Compton scattering formula. Applications of the Compton effect include uses in radiobiology, probing electron wave functions, and gamma spectroscopy.