H-index (also called H-index) is a mixed quantitative index, which was first proposed by Jorge Hirsch, a physicist at the University of California, San Diego, in 2005. Its purpose is to quantify the research results of researchers as independent individuals. Hirsch's original definition is that a scientist's H index means that among his published Np papers, H papers are cited at least H times, while the rest Np-h papers are cited less than or equal to H times (a scientist has at least one H index for his or her Np papers, and other (NP-H) papers have ≤ H citations).

H index is considered to be a great improvement on many previous measurement indexes; In the past, the measurement indicators often focused on the journals where researchers published their papers, so they all assumed that the author's contribution was equal to the average value of the journals. If a scientist's published achievements are ranked according to the number of life cycles cited, then the H index is a maximum, which means that each paper has been cited at least H times.

In addition, the Herfindal-Hirschman index, which is the abbreviation of HHI index, is the sum of the squares of the market share of all enterprises in a specific industry market.