The electron localization function ELF, which is crafted to reveal chemical bonds and their properties, has been generalized to the time-dependent regime. This allows the time-resolved visualization of the formation, modulation and breaking of bonds and gives thus insight into the dynamics of excited electrons. This has been illustrated by the π–π transition of ethyne induced by a laser field, and by the destruction of bonds and the formation of lone-pairs in a scattering process of a proton with ethene. In the second part, an optimal control algorithm is used to determine an optimized laser pulse of a HOMO–LUMO transition of the diatomic molecule lithium fluoride.