Foreshadowing is a dramatic device in which an important plot point is mentioned earlier in the story to return later in a sinificant way. This is said by Hermione Granger in A Very Potter Musical.
Snape: A person can however be a horcrux.
Harry: What's a horcrux?
Snape: I'm no even going to tell you Harry, you'll find out soon enough.
You find out later, Snape knew there were horcruxes concerning Harry. This exemplifies foreshadowing.
EDP445: I scared a 7 year old girl
EDP445: sends fucked up messages to an underage girl
people online: this is definitely one of the best examples of foreshadowing
A twisted cousin of foreshadowing and preshadowing but closer to foreshadowing
Foreshadowing episode one occurs specifically with a flashback of events before a story set by a character later in the story, more so in a TV show or a movie, that contains subtle hints to events already shown at an early point of the story, set later than the events of the flashback.
As the flashback is set further in the past, the subtle hints count as a foreshadowing
The killer’s father in episode 5 recalls the killer’s childhood. The killer is shown as a child playing with a toy gun. This is foreshadowing episode one where the killer murders someone as an adult