In this volume information relating to cratering and penetration in metallic targets has been gathered. Impact of compact particles, micro- particles, and rods at normal and oblique incidence on quasi-infinite targets and on thin targets, multiple spaced targets, and shielded targets is considered. Experimental data are presented in tabular and graphical form for ready references. Available theories and semi-empirical theories, as well as empirical correlation equations are summarized and compared with each other and with the experimental data. For normal impact on quasi-infinite targets 2 empirical correlation expressions ae deduced whih are more generally applicable than previous expressions. A qualitative description of the cratering process is given, and realistic regions of impact are defined. Recommendations for future experimental and theoretical work are made.