Recent studies in the field of surface reactions have provided evidence of the existence of transient hot precursors and their important roles in chemical processes. These precursors are generated by the trapping of atoms or molecules from the gas phase to a transient state on a surface and also by thermal- or photo-induced dissociation of admolecules. These precursors are translationally “hot” because they retain initial kinetic energy before trapping, and they further gain additional kinetic energy through the above exothermic trapping and dissociation processes. Before the dissipation of the energies into bulk, they migrate in lateral directions on the surface for a short time, then collide with co-adsorbed atoms or molecules and induce various subsequent chemical processes. Dynamics in these processes are being studied in various experimental and theoretical works. This article presents an overview of the recent progress made in this rapidly growing field, particularly with regard to application of angular and velocity distribution measurements of desorbing products and alignment of reactants on stepped surfaces.