Say's lawIn classical economics, Say's law, or the law of markets, is the claim that the production of a product creates demand for another product by providing something of value which can be exchanged for that other product. So, production is the source of demand. In his principal work, A Treatise on Political Economy (Traité d'économie politique, 1803), Jean-Baptiste Say wrote: "A product is no sooner created, than it, from that instant, affords a market for other products to the full extent of its own value.
OverproductionIn economics, overproduction, oversupply, excess of supply or glut refers to excess of supply over demand of products being offered to the market. This leads to lower prices and/or unsold goods along with the possibility of unemployment. The demand side equivalent is underconsumption; some consider supply and demand two sides to the same coin – excess supply is only relative to a given demand, and insufficient demand is only relative to a given supply – and thus consider overproduction and underconsumption equivalent.