Impact factor is an index to measure the influence of academic journals, which was put forward by Thomas Reuters in 1960s. The calculation method of the impact factor is to add up the cited times of papers published in a journal in the first two years, and then divide by the total number of papers published in the journal in the first two years. Therefore, the higher the impact factor, the more times the journal's papers are cited by other scholars, and the greater its influence.

The impact factor was originally used to help librarians evaluate the importance and value of periodical subscription, and now it has become one of the important indicators to evaluate the quality and influence of periodicals in academic circles. Impact factors are widely used to evaluate the ranking of journals, the academic achievements of authors and the performance of academic institutions.