Orwell wrote Animal Farm as an allegory, a symbolic representation of real events. Many characters and events in the novel symbolize people in the Russian Revolution and the Soviet Union. Here are some of the animals who symbolize individuals or groups in Soviet society: Mr. Jones (Russian Tsar and the aristocratic order); Old Major (Karl Marx and Vladimir Lenin); Napoleon (Stalin); Snowball (Trotsky); Squealer (the press); the pigs (ruling bureaucrats); and Moses the Raven (organized religion). Nearly all of the other animals represent the working class and Soviet peasants. For a more complete list, see the "Character" section.
The windmill represents the massive infrastructure constructions projects and modernization initiatives that Soviet leaders instituted immediately after the Russian Revolution. In Animal Farm, the windmill also comes to symbolize the pigs' totalitarian triumph: the other animals work to build the windmill thinking it will benefit everyone, and even after it benefits only the pigs the animals continue to believe that it benefits all the animals.