Bar formation process in interacting galaxies is reviewed on the basis of recent numerical simulations. I focus especially on the possible kinematical difference between tidally-induced bars and spontaneous bars: the former spans a wider range in the rotation rate, depending upon the parameters of the interaction as well as the internal structure of the host (i.e. perturbed) galaxy. I also discuss possible observational methods for discriminating between and weighing these two classes of galactic bars, including rotation rate measurements and environment statistics.