The Forever War, written by Joe Haldeman, is a classic space war science fiction novel. It tells the story of William Mandella, a soldier who is sent to fight in an interstellar war against an alien race known as the Taurans. Due to the time dilation effects of space travel, Mandella experiences time passing differently than on Earth, leading to a series of disorienting and challenging experiences. The Forever War is a poignant exploration of the human cost of war and the effects of time on relationships and society.