Image source: h-index from a plot of decreasing citations for numbered papers, Public Domain
The index was first proposed by J. E. Hirsch in 2005 and is defined as:
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. As an example, a researcher with an H-index of 15 has (of their total number of publications) 15 papers which have been cited at least 15 times each.
J.E. Hirsch's original article in which the h-index was proposed, published in Proceedings of the National Academy of Sciences of the United States of America. 2005; 102(46):16569-16572.
There are a number of limitations and cautions to be taken into account when using the H-index. These include:
The H-index can be calculated using the University of Toronto Library-subscribed databases Web of Science or Scopus, using Scoups free author lookup, or also using the My Citations feature of Google Scholar or the freely downloadable program Publish or Perish, which also takes its citation information from Google Scholar.
However if you wish to create a true H-index based on all unique citations to your publications from all sources, you will need to calculate it manually. The fewer papers you have the more significant each citation becomes in terms of calculating your H-index. Please contact Information Specialists for more information on this process.
Scopus provides citation tracking and a number of other visualization and analysis tools. Scopus is particularly useful for citations in the Sciences
Web of Science tracks citations across the Sciences, Social Sciences, and Humanities, and includes conference proceedings as well. The Web of Science is particularly useful for citations in the Sciences.
Google Scholar is useful for finding citations in books, grey literature, government and legal publications, and non-English resources. Google Scholar also indexes journals in the Sciences, Social Sciences, and Humanities, though the scope of this is unknown.
If you do not have a "My Citations" Profile, you can download the Publish or Perish software to calculate your Google Scholar h-index.
A commentary on the h-index by Professor Ann-Wil Harzing of the University of Melbourne (2008). Also discusses other indicies used to calculate researcher impact.