The H Index was developed by
The h-index is based on a list of publications ranked in descending order by the times cited. The value of H is equal to the number of papers (N) in the list that have N or more citations.
The h-index is calculated by the number of publications and the number of citations received. For example, an h index of 20 means there are 20 items, that have 20 citations or more.
J. E. Hirsch . An index to quantify an individual's scientific research output. PNAS November 15, 2005 vol. 102 no. 46