The story of the animals on the farm, which is described briefly and mainly through their basic character traits, begins in an environment where much time has passed since they remember freedom. Slavery under the farmer Mr. Jones has become a habit. Most animals are unaware of better or worse days, and some who understand have acquired a pessimistic or submissive attitude. Old Major, a pig who has had the fortune to live longer than other animals and is nearing the end of his life, feels that he must take action. He gathers the animals and gives them a reason that fills them with pride, reminds them of a revolutionary song they had forgotten ("Beasts of England"), and most importantly, puts them in thoughts about the future; revolutionary thoughts.
The pigs are the brains of the farm. Mainly guided by Snowball, a brave pig, they manage to carry out the Revolution and the farm becomes Free. The political scene that follows is generally optimistic, with difficulties not lacking, but the pigs gradually gaining primary power and control of the farm. However, the atmosphere remains positive.
The big turning point comes when Snowball's main political opponent, Napoleon, another pig who almost always disagreed with Snowball - unless the question was about why the pigs should have more food - manages to overthrow the government of the farm and establish a dictatorship under his name. Various dogs that he had raised from a young age provided great help, one could say military help.
The story unfolds with the tyrant gaining more and more power, restricting more and more freedoms that had come after the revolution, revising more and more laws that they had established (in the form of seven commandments), and generally making life more and more unbearable for the animals. Propaganda (mainly through the speeches and justifications of Squealer, another pig) was also in constant use to appease the doubts that occasionally arose. An important milestone in this course is the sale of a horse, Boxer, to a horse slaughterer when he had fallen ill. Boxer was the hardest-working animal and the most loyal follower of the tyrant and the Revolution (which he believed in until the end, or until shortly before the end).
The climax of the downfall and the end of the story comes when the animals watch a closed-door meeting of the pigs with the human masters of neighboring farms (symbols of states or state alliances). The pigs had already started walking on two legs (something they had established as "bad" but recently revised) and soon reached an agreement with the humans. Ultimately, nothing bad had happened on Animal Farm; the animals were enslaved just like before. In fact, now they are enslaved with the latest methods; an example for other farms. Napoleon declares that Animal Farm will now be called Manor Farm, as it was in the days of Mr. Jones.
The animals who secretly watched the meal looked from pig to human, from human to pig, and from pig to human again; they found no difference.