J. E. Hirsch proposes the "h-index" as a measure to quantify an individual's scientific research output. The h-index is defined as the number of papers with at least h citations each, where h is the highest number of citations any single paper has received. This index is proposed to be a simple and useful way to characterize a researcher's scientific impact, especially in fields like physics. Hirsch argues that the h-index is superior to other single-number criteria such as the total number of papers or total citations, as it measures both the quantity and quality of a researcher's work. The h-index can be easily calculated and provides a ballpark estimate of the total number of citations. Hirsch also discusses the relationship between the h-index and time, suggesting that the h-index should increase linearly with time for researchers who maintain a steady publication rate. He provides empirical data on the h-indices of prominent physicists and concludes that a high h-index is a reliable indicator of significant scientific achievement. The h-index is also extended to groups of scientists, and its application in biological and biomedical sciences is discussed. Overall, the h-index is presented as a useful tool for evaluating and comparing the scientific impact of researchers.J. E. Hirsch proposes the "h-index" as a measure to quantify an individual's scientific research output. The h-index is defined as the number of papers with at least h citations each, where h is the highest number of citations any single paper has received. This index is proposed to be a simple and useful way to characterize a researcher's scientific impact, especially in fields like physics. Hirsch argues that the h-index is superior to other single-number criteria such as the total number of papers or total citations, as it measures both the quantity and quality of a researcher's work. The h-index can be easily calculated and provides a ballpark estimate of the total number of citations. Hirsch also discusses the relationship between the h-index and time, suggesting that the h-index should increase linearly with time for researchers who maintain a steady publication rate. He provides empirical data on the h-indices of prominent physicists and concludes that a high h-index is a reliable indicator of significant scientific achievement. The h-index is also extended to groups of scientists, and its application in biological and biomedical sciences is discussed. Overall, the h-index is presented as a useful tool for evaluating and comparing the scientific impact of researchers.