What's happening? What actually is a commodity? You would think that this question should have a simple answer, but as ever in the investment world, nothing is that straightforward. A commodity is almost anything that is tradeable. But as far as markets are concerned, it normally refers to the basic items of life, from 'soft' commodities such as food and drink through to metal ores and gold. Essentially, if it is not nailed down, it is probably a tradeable commodity – and that probably includes the nail. Digging deep: Rio Tinto is a well-diversified FTSE100 mining giant, and a leading producer of the three most-consumed industrial metals