In popular terminology, Marxism is a set of beliefs about the proper set up for a country’s economy. Marxism is diametrically opposed to capitalism, arguing that capitalism is unjust because it exploits the workers. Although this is somewhat controversial, we can at least argue that Marxism affects the American economy by inspiring government programs like welfare programs and Medicaid.
Marxism is named for Karl Marx, who laid out the foundations of the philosophy in the mid-1800s. He argued that capitalism inherently exploits the workers. Marx argued that manufactured goods only had value because of the work that went into them. Even so, the workers did not get most of the money from the sale of the products they made. Instead, the capitalists who owned the factory got most of the money even though they did none of the work. To Marx, this was very unjust. He argued that the economy should be set up in such a way that the workers would own everything and there would be no capitalists. In this system, everyone would be essentially equal to one another economically. There would be no rich and no poor people. Only in this way could there be a truly just economic system.
Today, it is very controversial to call any aspect of our economy Marxist. This is because Americans generally hate the idea of Marxism so calling something Marxist is very politically inflammatory. However, you can argue that some aspects of our economy are influenced by Marxism. In particular, you can say that anything the government tries to do to bring about economic equality is Marxist. Therefore, you can say that programs like welfare, Medicaid, and Social Security are evidence of the influence of Marxism on our economy.