Since the 1990s, there has been a resurgence of interest in non-collapse theories. Interpretations of quantum mechanics now mostly fall into the categories of collapse theories (including the Copenhagen interpretation), hidden variables ("Bohm-like"), many-worlds ("Everettian") and quantum information approaches. While collapse theories continue to be seen as the default or mainstream position, there is no longer any clear dichotomy between "orthodox" and "unorthodox" views. The Stanford Encyclopedia as of 2015 groups interpretations of quantum mechanics into five classes (all of which contain further divisions): "Bohmian mechanics" (pilot-wave theories), " collapse theories ", "many-worlds interpretations", " modal interpretations " and "relational interpretations".