Science fiction tropes are common themes or concepts that frequently appear in science fiction literature, films, and other media. These tropes help to establish familiar settings and scenarios, making it easier for audiences to engage with the story. Examples include time travel, alien encounters, and dystopian futures, which often explore the implications of advanced technology or societal changes. These tropes can serve various purposes, such as highlighting moral dilemmas, exploring human nature, or imagining future possibilities. While some tropes may become clichéd over time, they can also be reinterpreted or subverted to create fresh narratives.