Sci-Fi and Fantasy
Science fiction is a re-imagining of ideas and technologies that we haven't seen yet, but still fit within our understanding of the universe. Themes can include space travel, time travel, robots, cyborgs, cyberpunk, parallel realities, etc.
The fantasy genre does not necessarily have any grounding in reality, and is more concerned with magic and myth. This can encompass everything from historical Arthurian tales of court intrigue, to epic battles for empires and crusades against the forces of darkness.