Science fiction (abbreviated SF or sci-fi with varying punctuation and case) is a broad genre of fiction that often involves sociological and technical speculations based on current or future science or technology. This is a reader-selected collection of short stories, originally published between 1960 and 1963, that entered the US public domain when their copyright was not renewed. Summary by Cori Samuel, with Wikipedia input.
Note: This collection originally included a tenth story, The Burning Bridge by Poul Anderson. That recording was removed in November 2011 because of a copyright claim.