Prophecies are predictions about the future as foretold by an oracle, seer, fortune-teller, religious text, or other source. Prophecies are common worldbuilding elements and are often used in narrative-driven worlds to drive the plot. They may be true, they may be false, and they are often composed in such a way that there are many interpretations. Common prophecies involve the ascension of a hero or ruler, the end of the world, or the coming of a god or otherworldly abomination.
If including prophecies in your own fictional world, consider how understandable they are, if they are true or not, who believes them, and who is trying to either bring them to pass or keep them from occurring.
Prophecies may revolve around an important item or event.