  High resolution images at different wavelengths show the common presence of
structures and microstructures in planetary nebulae (PNe), which are not well
incorporated to the existing models for the formation of these objects. We
summarize how studies of the internal kinematics, combined with the information
provided by high resolution images, may help to establish the nature and
possible origin of the observed structures as well as to provide information
about the physical processes involved in the formation and evolution of PNe.
