AbstractSince the introduction of the Tooth Positioner (TP Orthodontics) in 1944, removable appliances analogous to clear aligners have been employed for mild to moderate orthodontic tooth movements. Clear aligner therapy has been a part of orthodontic practice for decades, but has, particularly since the introduction of Invisalign appliances (Align Technology) in 1998, become an increasingly common addition to the orthodontic armamentarium. An internet search reveals at least 27 different clear aligner products currently on offer for orthodontic treatment. The present paper will highlight the increasing popularity of clear aligner appliances, as well as the clinical scope and the limitations of aligner therapy in general. Further, the paper will outline the differences between the various types of clear aligner products currently available.