Marx’s understanding of commodity (product of labor intended for exchange) is central to understanding his ideas about the nature of capitalism. For Marx commodities produced to subsist and to satisfy their needs have use value. Under capitalism and the capitalist mode of production, where workers produce for others and exchange commodities for money, products have exchange value. Because it is often unclear where a commodity’s value comes from, it takes on an independent, external reality. Marx called this the fetishism of commodities, when the value of an object or commodity is believed to be tied to something “natural” or independent of human action, such as markets. Thus, the reality that value originates from labor and the satisfaction of needs is obscured. Marx used the term reification to describe the process whereby social structures become naturalized, absolute, independent of human action, and unchangeable. Just as the fetishism of commodities obscures the relationship between commodities, value, and human labor, reification obscures the underlying relationships within the capitalist system and allows supposedly natural and objective social structures to dominate people. The nature of commodity under the capitalist mode of production is closely related to what Marx described as the alienation of the workers from their product of labor.
More summaries of Marx's writings and ideas:
An Extended Summary of The Communist Manifesto by Marx and Engels (chapter 1, chapter 2, chapters 3 and 4)