A commodity is something for which there is demand, but which is supplied without qualitative differentiation across a market. It is a product that is the same no matter who produces it, such as petroleum, notebook paper, or milk. In other words, copper is copper. The price of copper is universal, and fluctuates daily based on global supply and demand. Stereos, on the other hand, have many levels of quality. And, the better a stereo is [perceived to be], the more it will cost.

One of the characteristics of a commodity good is that its price is determined as a function of its market as a whole. Well-established physical commodities have actively traded spot and derivative markets. Generally, these are basic resources and agricultural products such as iron ore, crude oil, coal, ethanol, salt, sugar, coffee beans, soybeans, aluminum, rice, wheat, gold and silver.

Commoditization occurs as a goods or services market loses differentiation across its supply base, often by the diffusion of the intellectual capital necessary to acquire or produce it efficiently. As such, goods that formerly carried premium margins for market participants have become commodities, such as generic pharmaceuticals and silicon chips.