This review summarizes the current understanding of transpolar arcs. The following topics are covered: (1) transpolar arcs types; (2) influence of IMF By and Bz on shape and motion of transpolar arcs; (3) temporal intensifications of transpolar arcs; (4) substorms and transpolar arcs; (5) solar wind energy coupling; (6) ionospheric convection and source regions of transpolar arcs; (7) interhemispheric differences caused by IMF Bx and (8) the Earth dipole tilt; (9) magnetotail topology during transpolar arcs.We investigate how substorms with and without growth-phase pseudobreakups are affected by solar wind and ionospheric conditions. The study is based on 874 events identified with Polar UVI.