Using citation metrics to determine author impact can help scholars not only identify significant researchers in their field, but also provide one indicator of an author's perceived value - by demonstrating where and how their work has been cited. Citation metrics have been applied for purposes of hiring, promotion, and enture.
Citation indexes can be used to:
The h-index is an index that attempts to measure both the productivity and citation impact of the published body of work of a scientist or scholar. The index is based on the set of the scientists's most cited papers and the number of citations that they have received in other publications.
A scientist has index h if h of his/her Np papers have at least h citations each, and the other (Np - h) papers have no more than h citations each.
The h-index as a way to measure scholarly impact and predict scholarly success. Wired, September 12, 2012.