The article describes the visualization of the dynamics of supercoiled DNA, with particular focus on the formation and movements of plectoneme DNA loops. In the experiment, plectonemes are created in fluorescently labeled DNA molecules with magnetic tweezers and imaged. Topics include the influence of stretching force and ionic strength on plectoneme formation, the movements of plectonemes along DNA via diffusion or hopping to new locations, and the role of plectoneme dynamics in genomic conformation and genetic processes.