Science fiction, to me, is fiction that is based on the idea of future science. For example, Star Wars is not Science Fiction by my standards. It is Fantasy. Not Science Fantasy, just Fantasy. It has magic, and machines that defy what is possible. Attempts to make it sci-fi are what has muddled the expanded universe. Star Trek, on the other hand, is science fiction. Most of the techno-babble used in the show has a foundation in science, and could eventually be realities. The writers, led by Gene, attempted to paint a bright future for what humanity has in store. They even were able to explain why there were several humanoid aliens with a realistic explanation.