There are many themes that George Orwell often discusses in his works. However, three of the most important ones are social injustice, the dangers of totalitarianism and technology. All of these themes are evident in works such as Animal Farm and 1984.
The topic of social injustice can be seen in Animal Farm when we look at the way in which the pigs take advantage of the revolution. Although the farm animals risked their livelihood when they rebelled, and despite the fact that they worked hard to make the farm profitable after it was taken from the farmer, they receive little reward. Most of the benefits of their new "liberty" go to the pigs, in a display of social injustice that resembles the way the high classes take advantage of the lower classes in reality.
The dangers of totalitarianism are evident in 1984. In this book, Big Brother has such total control of society that people are not able to enjoy freedom even in their private life or their private thoughts. Orwell was concerned about communists regimes being able to gain such absolute power.
Finally, the topic of technology can be seen in 1984 as well. Part of the reason why the Party is able to gain so much control is due to their use of technology, such as their propaganda or their manipulation of the social environment of the inhabitants.