Stories about the new generation of witches and wizards after the second war. Often focused on the children of the trio or others at Hogwarts with them.
General Fiction stories set after the Trio's years at assumed 7th year at Hogwarts, typically after the fall of Voldemort, often Next Generation stories.
General Fiction stories about Marauders and other Marauder Generation characters [Snape, Lily, etc] taking place prior to Voldemort's first fall, typically set during the Marauder's years at Hogwarts.
General Fiction stories that take place in the past, typically anything Pre-Marauder, ie. Founder Era, Dumbledore-centric, Riddle-centric, McGonagall-centric.