Coined in: J. Priem, D. Taraborelli, P. Groth, C. Neylon (2010), Altmetrics: A manifesto, (v.1.0), 26 October 2010. http://altmetrics.org/manifesto. The manifesto and hashtag were the first use of the term, though not of the idea of tracking impact from new measures, which arose in 2008-09.
To complement - not replace! - traditional journal/scholar metrics that don’t include internet-based mentions of scholarly articles
Article-level, not journal
Web-born (especially open access)
Bookmarks in research tools