A commodity is anything for which there is demand, but which is supplied without qualitative differentiation across a market. In other words, copper is copper. Rice is rice. Stereos, on the other hand, come in many varieties of quality. And, the better a stereo is, the more it will cost. Whereas, the price of copper is universal, and fluctuates daily based on global supply and demand.
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, 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.
Linguistically, the word commodity came into use in English in the 15th century, derived from the French word "commodité", similar in meaning to "convenience" in terms of quality of services. The Latin root meaning is commoditas, referring variously to the appropriate measure of something; a fitting state, time or condition; a good quality; efficaciousness or propriety; and advantage, or benefit. The German equivalent is die Ware, i.e. wares or goods offered for sale. The French equivalent is "produit de base" or "matière première" like energy, goods, or industrial raw materials.
A commodity's value changes over time.