It is a series of links connecting the many places of production and distribution and resulting in a commodity that is then exchanged on the world market.
[1] A number of commentators have remarked that in the Internet age commodity chains are becoming increasingly more transparent.
The Wikichains.org project has adopted the same wiki technology used by Wikipedia in order to help make commodity chains more transparent.
"They are a network of labour and production processes whose end result is a finished commodity".
Rather than a linear chain, a circuit-board is a better metaphor for this concept because things are interconnected in so many ways, not just a mere straight line.