An Easter egg in a game, movie, book, or other media refers to a hidden reference, message, or element that creators include for fans to discover. These Easter eggs often pay tribute to other works, offer a playful surprise, or provide additional content that is not part of the main storyline. In games, they might include secret levels or hidden items, while in movies or books, they could be subtle references to past works, inside jokes, or clues about the plot. Easter eggs are meant to reward attentive or dedicated fans who look closely for these hidden gems.