This document discusses the three main interactions that occur when x-rays interact with matter: coherent scattering, photoelectric absorption, and Compton scattering. Coherent scattering accounts for 7% of interactions and causes minimal scattering. Photoelectric absorption is important for image formation and accounts for 27% of interactions. Compton scattering leads to the most scattering and accounts for 57% of interactions in dental x-rays. The document provides details on the mechanisms of each interaction type.