The science-fiction genre represents a playground of scientifically inspired speculation and technologically substantiated escapism. Its a genre comprised equally of literary masterworks and commercial page-turners; a genre that varies philosophically almost as much as it does stylistically, and a genre that happens to include some of the greatest works of fiction to have ever been written. Of course, the genre itself is incredibly vast and equally daunting. If youre not already an avid reader, you may not know where to begin. 20,000 Leagues Under the Sea and the Forever War couldnt be more distinct from one another; neither could Amnesia Moon and the Female Man, or the Handmaid's Tale and The Moon is a Harsh Mistress. Honestly, its a complex world. Like any other kind of literature, the genre itself is divided into sub-genres that each differ drastically from the last, varying in terms of everything from metaphysical and ethical concerns, political dimensions and narrative intricacies. If you dont know where to start, or youre just looking for something new to read, here are 10 essential sci-fi novels that need to be read.