The final stage in technology development is sale. The sales phase is the true test of whether a new technological development will be important or relevant to a society. This brings us to the topic of economics. Economics is the study of production, distribution, sale, and consumption of goods and services. Supply and demand are the major principles in economics. Supply is the amount of a product that is available for sell. Demand is how much people want or need that product. For a technological innovation to be successful, it must be assigned a price where the factory can make just enough of the product that the people are willing to pay to have it. If the innovation is overpriced, people will not pay for it and the innovation will fizzle out and be of no good to anyone. If the price of the innovation is underpriced, the producer will not be able to make enough money from selling the product to pay the costs in making it. The producer will go bankrupt, stop making the product, and the innovation again, is no good to anyone.