Animal Farm is based on the Russian Revolution and corruption that occured after.
The main characters of the book are based on Russian leaders such as Joseph Starling (Napoleon), Leon Trotsky (Snowball) and Lenin. It is basically about totalitarianism (political system where there is only one party, allows no opposition, controls everything) Even though the animals have errected a sign with rules such as "All animals are equal" the irony is that they are not all equal, as demonstrated by the pigs! Hope this helps.