Here you can read George Orwell's novel, published in 1945.
Animal Farm is an allegory, which is a story in which concrete and specific characters and situations stand for other characters and situations so as to make a point about them. The book reflects events leading up to the Russian Revolution of 1917 and then on into the Stalinist era of the Soviet Union.
The setting of Animal Farm is a dystopia, which is an imagined world that is far worse than our own, as opposed to a utopia, which is an ideal place or state. Other dystopian novels include Ray Bradbury's Fahrenheit 451, and George Orwell's own 1984.
Here you can find a detailed analysis of this novel.