Author-level metrics attempt to quantify an author's impact, by analyzing (in different ways and over different amounts of time) how frequently their articles are cited.
Pros: These metrics can give a more holistic idea of author impact, across different journal titles.
Cons: These metrics are biased toward more prolific and more established authors. They also are not generalizable across disciplines.
Google Scholar Citations is available at: http://scholar.google.com/citations
It has the following features:
The h-index is the primary author-level metric. It represents the number of articles published by an author that have been cited h times or more. For example, an author with an h-index of 15 has published 15 articles that have been cited 15 times or more.
Essential Science Indicators is available through the "Additional Tools" tab of the Web of Science interface. It offers these features:
An ORCID identifier (free, requires registration) provides a persistent, numerical identifier for authors, and allows them to identify, definitively, their works. ORCID identifiers are particularly helpful for authors with extremely common names, or names from languages with writing systems that are not Latin-based.