George Orwell’s Animal Farm is an allegory about the Russian Revolution and totalitarian governments in general.
The farm where the animals of the book live represent the country of Russia. Many animals represent people in real life, especially Snowball, old Major and Napoleon, that represent dominant figures of the Russian Revolution.
The farm was ruled by Mr. Jones, that represents Tsar Nicholas II. Mr. Jones (Tsar) had the idea that he was the only ruler of his farm (Russia) and despite the fact that the animals (people from Russia) were starving he was the incontestable ruler.
Old Major (Lenin) with the help of the other animals (people) start a revolution against Mr. Jones (human and Tsar), all ruled by the idea that all animals are equal, this represents The October Revolution of 1917. Seven Commandments of Animalism are created, between them, one says “four legs good, two legs bad”, showing their hate for humans.
Snowball (Trotski) understands that the only way that the revolution of the animals gets to its objective is making a series of revolutions especially making improvements at the farm so it runs more efficiently. But Napoleon (Stalin) doesn’t like Snowball, he doesn’t listen to his ideas and even pees at the windmill - one of Snowball’s improvements to the farm. Just like Trotski was killed, Snowball is chased off the farm by Napoleon with his dogs, that represent KGB (Russian secret service).
Eventually, just like Stalin, Napoleon becomes one of the world’s worst dictators, the dreams that Russia Revolution once dreamed do not come true, hunger and poverty come again - just like the failure of the 5-year plan - and the quote from the book tells all: some all animals are equal, but some are more equal than others.