Since its debut, Star Trek has become one of the most popular names in the history of science fiction entertainment, and one of the most popular franchises in television history, as well as popular culture.
Star Trek depicts an optimistic utopian future where humanity has united with other sentient species in the galaxy. The central characters are members of the United Federation of Planets, who explore the galaxy, encountering new worlds and civilizations.
The protagonists are essentially altruistic; however, the nature of the Galaxy is conflict. Many alien species abound in the universe, who try by military might, or by subterfuge, to destroy the Federation. Starfleet, the scientific, exploratory, and military arm of the Federation does its best to protect the Federation from alien threats.
Star Trek and its spin-offs have proved highly popular in television repeats, shown endlessly on TV stations in the US and worldwide. The show’s cultural impact goes far beyond its longevity and profitability. Star Trek conventions have become popular and fans have coined the term "Trekkies".
An entire subculture grew up around the show and, anecdotally, there are indications that Star Trek has influenced many peoples' lives. Phrases like "Beam me up, Scotty" have entered vernacular, and devices have arguably been inspired by fictional counterparts.