Squealer’s role on the farm is as propagandist. In other words, he is the pigs’ spokesperson. He is able to twist everything the pigs do into something that sounds positive to the other animals. Allegorically, Squealer symbolizes Leon Trotsky. Squealer is described as follows:
He was a brilliant talker, and when he was arguing some difficult point he had a way of skipping from side to side and whisking his tail which was somehow very persuasive. The others said of Squealer that he could turn black into white.
The idea of turning black into white is classic propaganda. For example, when the milk and apples that were supposed to be shared by everyone disappear, Squealer explains it away as follows:
"Comrades!" he cried. "You do not imagine, I hope, that we pigs are doing this in a spirit of selfishness and privilege? Many of us actually dislike milk and apples. I dislike them myself. Our sole object in taking these things is to preserve our health. Milk and apples (this has been proved by Science, comrades) contain substances absolutely necessary to the well-being of a pig. We pigs are brainworkers. The whole management and organisation of this farm depend on us.
The animals seem to accept his explanation, even though it is obviously ridiculous.
As the pigs gain more power, Napoleon makes fewer public appearances and Squealer makes his excuses.