This volume provides an overview of the latest advances in the field of ionization by electron and photon impact. The book contains 18 contributions of recent experimental, theoretical, and computational work on correlated processes that involve a wide range of targets, including atoms, molecules, clusters, and surfaces. It covers a broad range of current topics, such as multi-particle coincidence studies, in particular, (e,2e) and (e,3e) processes, photoionization with or without excitation, and multiphoton single and double ionization. Three chapters contain the following topics: anisotropy and polarization in Auger-electron emission, multiple ionization of atoms in strong fields, and theoretical and practical aspects of photoionization with excitation.