SCI and SCIE(SCI extended) are the extended editions of Science Citation Index and Science Citation Index respectively (that is, the online edition), which mainly include the most influential and important journals in the fields of natural science and engineering technology, including more than 2,000 peripheral journals.

ISI publishes JCR (Journal Citation Report) every year. JCR counts and calculates the citations and cited data in more than 8,000 journals (online edition), including 3,800 core journals (CD-ROM edition) collected by SCI, and defines the impact factors and other indicators for each journal to report.

Impact factor (IF) is a data in American ISI (institute for scientific information) JCR (Journal Citation Report). That is, the total number of citations of papers published by a journal in the first two years divided by the total number of papers published by the journal in these two years. This is an internationally accepted periodical evaluation index.

The impact factor has become a general index of periodical evaluation in the world. It is not only an index to measure the usefulness and exhibition of periodicals, but also an important index to measure the academic level of periodicals and even the quality of papers. The influence factor is a relative statistic.

Reference from Baidu Encyclopedia