JFactory is the Joomla! Platform class, giving you access to the most important (mostly singletons) parts in Joomla. Use this tag when you have issues relating to the class. For issues pertaining to individual methods within the class, using tags such as jdocument, jdatabase, user, jdate, jmail, configuration, or jsession may be a suitable replacement or an accompaniment.
As of Joomla 3.9 there are the following methods in the JFactory Class:
Cited Resource: https://docs.joomla.org/Using_the_JFactory_class
Note: Methods are changing within this class in Joomla 4, see some discussion here: JFactory::getDbo() deprecated— what's the replacement?