(1) The function of identifying the source of goods or the identification of trademarks is the basic and primary function of trademarks. Trademarks are produced only by identifying the source of goods, so those who have this function can become trademarks. (2) The function of promoting sales. Producers and operators use trademarks to indicate the source of goods. Consumers use trademarks to distinguish similar goods, understand goods and make choices. In this way, trademarks have become an important tool to open up markets and compete in the market. (3) Functional producers who guarantee the quality of goods indicate that goods are provided by themselves, service providers indicate that a service is provided by themselves through trademarks, and consumers also identify goods or services through trademarks to identify their quality. This identification is related to the rise and fall of producers and operators, which can promote production and operation to pay attention to quality and maintain quality stability. (4) The function of advertising. Modern commercial propaganda is often centered on trademarks, which release commodity information and promote commodities, stand out, be concise and easy to remember, attract consumers' attention and deepen their impression of commodities. (5) Functional trademarks that establish business reputation are used to show the source of goods, ensure the quality of goods, and advertise goods as an effective means to open up markets, which shows that trademarks condense the reputation of the goods marked by them and the producers and operators of the goods, and trademarks are the best marks of the reputation of goods and related enterprises.