Created by Google Scholar and used in Google's My Citations feature.
i10-Index = the number of publications with at least 10 citations.
This very simple measure is only used by Google Scholar, and is another way to help gauge the productivity of a scholar.
Advantages of i10-Index
Disadvantages of i10-Index
Here is a screenshot of a Google Scholar My Citations page for Charles Darwin (you can see the i10-Index highlighted in the small table):