An Open Ending (OE) means the author intentionally withholds final answers — the fate of a character, a relationship, or a plot is left for the reader to decide. OE is a craft choice, not laziness, and is common in literary fiction, dystopia and sci-fi.
If you enjoy books that keep generating discussion after the last page, OE is for you. If you need closure, OE can be frustrating. The list below flags how open each ending is and what triggers to expect.