The other two similar methods are that economists divide economic development into two stages: pre-industrial society and post-industrial society. Basically the same as the three-level industrial division method, in the post-industrial society, people are mainly engaged in the service industry, and its essence is to provide various services. People use wisdom and creativity and rely on information technology to provide services to customers through different social organizations. Information becomes a key resource. The service industry is not limited to catering and hotel services, but generally includes five activities: (1) business services, such as consulting, finance, banking and real estate.
(2) Trade services: retail, maintenance, etc.
(3) Infrastructure services: transportation, etc.
(4) Social services: catering, medical care, etc.
(5) Public services: education, public utilities, government, etc. (Excerpted from Production Management, page 5)
Marx divided human activities into production, exchange, distribution and consumption, while service industry involved exchange, distribution and consumption.
Now people put forward the fourth industry, which is to separate the information industry from the tertiary industry, but in fact the information industry also belongs to the service industry, such as consulting and education. Therefore, we believe that the service industry is an industry that does not manufacture but may provide tangible products. It cannot be stocked, transported separately and directly measured. It has timely market demand and feedback demand, and the market is relatively small. (Description of production and operation management)