Robert Anson Heinlein was an American science-fiction author, aeronautical engineer, and retired Naval officer who is known as the "dean of science fiction writers". His works emphasized scientific accuracy, pioneering hard science fiction, and expressed admiration for competence and critical thinking.He was one of the best-selling science-fiction novelists for many decades and is often considered one of the "Big Three" of English-language science fiction authors along with Isaac Asimov and Arthur C. Clarke.Heinlein's work continues to have a significant influence on the science-fiction genre and modern culture more generally. He coined terms that have become part of the English language, such as "grok", "waldo", and "speculative fiction", and popularized existing terms like "TANSTAAFL", "pay it forward", and "space marine". He anticipated technologies such as mechanical computer-aided design and the modern cellphone in his writing.Four of Heinlein's novels won Hugo Awards, and he was named the first Science Fiction and Fantasy Writers Association (SFWA) Grand Master in 1974. Seven of his works were awarded "Retro Hugos" fifty years after publication. Heinlein repeatedly addressed social themes such as individual liberty and self-reliance, the nature of sexual relationships, and the influence of organized religion on culture and government within the framework of his science-fiction stories.He died in Carmel, California in 1988.