Class struggle appeared all throughout history. At first, people lived in small communist societies. Then, they took property from the Earth for themselves and started to use slaves. They then had feudalism, which meant one person owned an entire area of land and used soldiers and workers to help them make money, and only gave their workers land, but they had some freedom that slaves didn't. Finally, in Karl Marx's time, people in some countries were becoming workers and bosses during the industrial revolution. The bosses owned the machines that the workers used to make things, but they didn't help using the machines. Instead, they made money by buying the time and energy of the workers to make things. Marx believed that the workers were not making as much money as they deserved because the boss would make money from the work they did without helping.