Science fiction is an imaginative genre that explores speculative concepts such as space travel, time travel, and extraterrestrial life. It uses scientific ideas and human problems/solutions as a basis for stories, even if the science itself is fictional. Some key developments in science fiction include the first use of the term "sci-fi" in 1954, early works like Lucian's True History in the 2nd century AD, and the genre solidifying in the 21st century with many movies based on science fiction concepts. Now the genre influences popular culture and entertains questions about whether science fiction concepts could become reality.