When franchise creator Gene Roddenberry resurrected his spacefaring series 20 years after the initial pilot debuted, he defied the odds. However, it was Star Trek: Deep Space Nine, the third series set in this universe, that made it a "real" franchise. The fourth series in the universe, DS9 didn't just prove The Next Generation wasn't a fluke -- it showed that Star Trek had a future beyond the starship Enterprise.
Source：https://www.cbr.com/deep-space-nine-star-trek-real-franchise/
