A sci-fi novel is classified as a 'space opera' when it weaves an epic narrative that unfolds in a vast, often interstellar setting, incorporating elements of adventure, romance, and political intrigue. 'Underrated Space Operas In Sci-Fi Literature' are those that, despite their grand scale and intricate storytelling, may not have garnered the widespread recognition they deserve. These narratives typically feature complex characters, advanced technology, and sprawling galactic empires, offering a grand stage for exploring profound themes such as the nature of existence, the ethics of technology, and the moral dilemmas of space exploration. Despite their underrated status, these space operas have significantly influenced the genre and continue to inspire other forms of media with their rich thematic depth and imaginative world-building.