A: Enterprises charge different prices to different customers who buy the same commodity. We call this method price discrimination. The fundamental reason of price discrimination is that monopoly enterprises are facing the decline of demand curve, and different people are willing to pay different prices for this commodity. If enterprises can distinguish different types of consumers, then they can implement price discrimination. According to the degree of price discrimination, we can divide price discrimination into the following three types:

(1) First-class price discrimination

This kind of price discrimination, also known as complete price discrimination, refers to the pricing of completely monopolized enterprises according to the highest price that different consumers are willing to pay for different quantities of goods, that is, according to the demand price. However, because it is difficult for enterprises to charge different prices for products per unit quantity, first-class price discrimination is rare in real life.

(2) second degree price discrimination

Second-degree price discrimination refers to completely monopolized enterprises that sell different quantities and grades of products at different prices, but consumers who buy the same quantity and grade of products pay the same price. Second degree price discrimination's profit is less than the first-class price discrimination, but greater than the same monopoly price.

(3) Three-level price discrimination

Three-level price discrimination refers to completely monopolized enterprises setting different prices for different types of consumers. The implementation of three-level price discrimination must meet two basic conditions: ① manufacturers can distinguish different types of consumers and ensure that goods do not circulate among different types of consumers; ② Different types of consumers have different demand elasticity. To implement three-level price discrimination, it is still necessary to make the marginal income of each market equal to the marginal cost of the enterprise according to the principle of MR=Mc, and the selling price of different markets depends on their respective demand curves.

We often see this kind of price discrimination in our life. For example, a few years ago, many tourist attractions charged higher fares for foreign guests, because foreigners and China people are easy to distinguish, and foreigners traveling in China will have less flexible demand for tourist attractions.

There are also some hidden price discrimination, which may appear in other forms, such as discount coupons, which are actually price discrimination against people who do not have discount coupons. These people's demand price elasticity is small, and they even buy goods without discount, while those with high demand price elasticity will spend some energy looking for discount coupons, and they may not buy goods without discount coupons.