Altmetrics,  or "alternative metrics" are a measure of research dissemination and an indicator of impact, combining traditional impact factors and measures with emerging and evolving methods of scholarly dissemination, such as views and downloads from social media sites. They are metrics that complement traditional metrics such as citation counts to capture the impact within the scholarly community and beyond, such as practitioner or policy impact.

Depending on the tool used (Altmetric.com, PlumX, ImpactStory etc.) altmetrics can measure different types of engagement from many different sources:

Usage: Views, downloads (Figshare, Dryad, Slideshare)

Captures: Mendeley bookmarks, CiteULike bookmarks

Mentions: Blog posts, news stories, policy documents, Wikipedia articles, comments, reviews

Social Media: Tweets, Facebook mentions, shares

*Like any metric, there is a potential to "game the system" by artificially inflating metrics to show more use and dissemination than what is occurring naturally.