What are some contributions to society that Karl Marx made?

Whether or not one describes oneself as a Marxist, there can be little doubt Karl Marx hugely influenced a number of disciplines. Economics, history, sociology, philosophy, and politics have all been touched by the Marxist spirit of inquiry.
In relation to society, Marx was especially influential, in that he broadened our understanding of what society is and how it came into being. The governing principle Marx uses is that of materialism. This does not mean, as it tends to do today, an obsession with material wealth and goods. What Marx means by materialism is that material conditions or economic factors determine the structure of society. That is, if we look at society, we see there are various classes, and each one of those classes is determined by material, or economic, causes.
Marx's overview of society is historical. He sets out to show precisely how societies came into being over time and how they are likely to develop in the future as capitalism degenerates, thus unleashing revolutionary social change. In the present day, this may not seem a particularly controversial approach, but at the time it was extremely radical. Traditionally, societies were viewed as being an organic whole, almost like expressions of the divine will from time immemorial. Marx challenged the prevailing conception of society, demonstrating not just how societies came into being, but also how they would inevitably change as capitalism's inherent contradictions lead to its replacement by communism. In both cases, acknowledgment of material factors is crucial to developing one's understanding.
Classes are to be understood by their relations to the means of production. What does Marx mean by this? He simply means those things used to generate economic value such as factories, equipment, and machinery. The capitalist class owns the means of production, enabling it to exploit the proletariat, or working classes. The means of production in turn generate what Marx calls relations of production. These are the social relationships individuals must enter into if they are to survive within the capitalist system. So, for instance, in a factory owned by capitalists, there would be a distinct hierarchy of employers and employees, bosses and workers.
Also, a later generation of Marxist feminists would see gender relations as being determined by relations of production. They felt women's overall subjection in society needed to be explained by their relatively low position within the capitalist system or mode of production. The same analysis has been used to help explain systemic poverty and exploitation experienced by people of color.
This development in the Marxist analysis of society has given it a relevance to our times. Although society has undergone rapid change since the mid-nineteenth century, Marx's sociological thought still provides us with a useful tool for understanding the contradictions and ambiguities that lie at the heart of the capitalist system in society.
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