Imagine if you were to organise a market at school where you sold toys, sports equipment or computer accessories. With the money you would then be able to buy various other items from your fellow pupils or swap your merchandise for something else. If no one tells you what you are allowed to sell or at what price and quality, that is the basic idea of the free market. In an economic system based on the free market, the following principles apply: there is private property and a free market where sellers and buyers can trade freely (without political intervention or intervention by the state). That is the principle of "supply and demand”. These principles exist above all in democratic states, where the right to freedom is guaranteed in the constitution. The economic system in Germany is called a "social market economy”.