For questions related to commodities, commodity trading, etc. For specific trading questions, consider using a specific tag as well, e.g. futures, options, etc.
Gold is a prime example of a commodity, because all gold of the same karat rating is considered essentially the same, regardless of origin. Coffee is another example of a commodity, because although arabica and robusta, the two main species of coffee that underlie futures contracts, do differ, within species the financial markets treat them as identical.