Personalized service originated from e-commerce. 1999 Ten famous digital library experts and information technology experts of American Library and Technology Association listed personalized service as the top ten trends of digital library development.

In China, Zhao Jihai and Zhang Xiaolin's research paper 200 1 started, and the research on personalized service has been 14 years. Personalized service gradually moves towards humanization and intelligence from research to practice. See table 2- 1 for the related subject documents published by librarians in recent years.

Table 2- 1 Number of related literatures published over the years

Note: The retrieval point is "Library Personalization" in CNKI database.

Figure 2-12001-2014 Comparison of the number of personalized documents published in the library.

As can be seen from Figure 2- 1, from 200 1, the research on library personalization began to develop and showed an increasing trend year by year. In 20 10, the number of documents related to library personalized research reached a peak, with 2 15 in that year, and then decreased year by year. But generally speaking, personalized service is still one of the research focuses of library science.

Personalized service research ranges from "deepening user research and resource integration" to "research on technical development level" and then to "research on user service trend", which deeply excavates user behavior and provides users with predictive recommendations, and finally achieves the goal that users can get the required services by using various terminals without leaving home.