Progress in planetary lightning

We review the progress in the last decade in the field of planetary lightning. We provide background covering terrestrial lightning and newly discovered associated phenomena such as sprites. We concentrate on the theory and observations regarding lightning at Jupiter, especially the discoveries made by the Galileo orbiter and entry probe. Recent observations of Titan's atmosphere and a theory of possible lightning at Titan are reviewed. We discuss the potential for lightning detection by the Huygens probe that will enter Titan's atmosphere in 2005. Directions for future progress in planetary lightning are outlined.