Metrics:
E.g. Author A has an h-index 9. This means he/she has published at least 9 articles, every one of which has been cited at least 9 times.
E.g. Author A has an i10-index 9. This means that at least 9 of his/her articles have been cited at least 10 times.
E.g. Author A has citation count of 87. This means that you need to add up all times his/her work has been cited to calculate the Citation count.
What is the idea?
The more the author publishes and the more his/her work is being cited by other authors, the higher the index.
The idea for quantifying the impact of a researcher has always been a hot topic. Despite the drawbacks of the author-level metrics, the h-index and i10-index are fast-growing and frequently used.
Where to find them?
Scopus, Web of Science and Google Scholar and some other free online ranking resources.