Popular price, also known as standard price, refers to popular price, which means that the brand of a specific product is set in a certain area and will change with market fluctuations. Fair price is the result of market equilibrium. Public prices will change, not stay the same. The open price is the default price after the market is balanced. For example, it is suggested to retail the mineral water in 2 yuan, so people won't ask about the price. They just pay 1.5 yuan takes the mineral water away. Common price is the best pricing after market balance and screening, which is unified and universal. The appearance of fair price avoids the vicious price competition of suppliers and lays the foundation for market stability.