In summary, Animal Farm is a story about farm animals living on Manor Farm, owned by Mr. Jones. The animals face constant oppression and exploitation from Mr. Jones causing the animals to plan a revolt led by Snowball and Napoleon. The animals kick Mr. Jones from the farm, form the philosophy of Animalism, and create seven commandments for the animals to follow.
Mr. Jones comes back with men to try to take the farm back, but the animals win led by Snowball. Napoleon is concerned about Snowball's popularity and, during a meeting about building a windmill, Napoleon takes his chance to chase Snowball from Animal Farm and convinces the other animals that Snowball was a traitor. Napoleon takes complete control of Animal Farm by changing the seven commandments to fit his narrative.
Napoleon forces the other animals to complete the windmill, deals with revolts with harsh consequences, and kills animals he thinks are traitors. When the humans attack again, Napoleon forces the animals to defend and die for Animal Farm. Years pass, Napoleon and the pigs begin to act more and more like the humans that oppressed them before. There is no happy ending for the rest of the animals with the only commandment reading, All animals are equal, but some animals are more equal than others.
Here is the Animal Farm 1954 movie for those who rather watch the movie than read the original novel. Note some scenes in the original aren't in the film adaption and the movie is not meant to be a substitute for the original novel.
Fun fact Animal Farm is the only movie funded by the CIA.