Scholarly citations can be traced all the way back to the 15th century, but in the 21st century the internet, social media and the open access movement have made it easier than ever before for the public to engage with scholarly outputs. Altmetrics provide a measure of public engagement with web-native scholarship. They can be embedded into publishing platforms and institutional repositories as article-level metrics, and they provide evidence of impact for open access mandates.
Three leading altmetrics aggregators are discussed: Altmetric.com; ImpactStory.org; PlumAnalytics.com. An institutional systems approach is recommended to mitigate the "pond-mentality" of the growing number of sources that provide measures of impact for research output. Research profiling systems are able to harvest most of these ponds and so save time for the researcher and research manager. In addition, national profiling systems would leverage economies of scale to increase the visibility and impact of all players, making it easier for potential investors and collaborators to find research partners.
Altmetricians are challenged to develop a metric that measures the openness of a research entity.