The provided source, an excerpt titled "Investing in Epic Sci-Fi Television," functions as a critical guide to ten long-running science fiction television series that the author deems worthy of a significant time commitment. It begins by arguing that long-form sci-fi shows offer valuable viewing experiences through expansive narratives and intellectual themes. The bulk of the text consists of detailed summaries for each show—including Doctor Who, Star Trek: The Next Generation, and The Expanse—highlighting their episode counts, unique strengths, and key characters. Ultimately, the guide suggests these series are worthwhile investments due to their rich narratives and cultural impact on the genre, concluding with advice on how newcomers can approach these lengthy commitments.