Most people are aware that Animal Farm is a satire of the Russian Revolution. Most of the characters in the story can be traced to real historical figures. For example, Lenin and Trotsky are represented as Old Major (also Marx) and Snowball and Stalin is Napoleon. Even the dates of the revolutions coincide, at least in terms of the October revolution.
The story is also a satire of revolutions in general. Take away the Russian resemblances and it is basically the story of every revolution that failed. It is also a cautionary tale. We read the story and realize that idealism is hard to maintain into reality.