In such a true-amplitude migration, the geometrical spreading effects are removed from the input data during the imaging process and, thus, reflector amplitudes become basically a measure of the angle-dependent reflection coefficient. Commencing with the basics of wave propagation and ray theory, a complete description of Kirchhoff migration is presented. By relating the strict mathematical derivation of true-amplitude Kirchhoff migration to clear geometrical concepts, the gap between the originally graphical migration schemes and the nowadays available analytical descriptions based on a stationary-phase evaluation is closed. Further aspects relevant to the correct recovery of amplitudes in depth migration, such as the handling of topography and irregular geometries, are explained in a mathematical as well as in a geometrical manner. Finally, Kirchhoff migration is integrated into a seismic reflection imaging workflow based on the data-driven common-reflection-surface (CRS) stack method.