The literary device that gives readers a hint or clue about events that will happen later in a story is foreshadowing.
Foreshadowing plants suggestions, warnings, images, dialogue, or events that prepare the audience for what follows. A writer might give a character an ominous line, introduce an apparently unimportant object, change the setting, or even use a title or chapter heading as a clue. These signals build anticipation and dramatic tension.
One early example appears in the Book of Genesis: Joseph dreams that his brothers’ grain bundles bow to his. Later, when Joseph becomes vizier of Egypt, his brothers bow to him, fulfilling the dream’s hint. The clue can be obvious or subtle, and it may accurately predict an event or deliberately shape the audience’s expectations before subverting them.
Foreshadowing is not the same as a flashback, which presents past events, or a flashforward, which directly moves the narrative ahead in time. It also differs from a red herring, whose purpose is to mislead. Chekhov’s gun is a related principle: an introduced detail should later become necessary to the story.