Altmetrics, or alternative metrics, refer to article level measurement of non-traditional bibliometrics such as news and social media coverage and other non-scholarly venues. These are generally considered to be a complement to more traditional citation impact metrics, like impact factors and SJR numbers. Projects such as Our Research (formerly called ImpactStory) and various commercial services have grown up around the concept (Altmetric andPlum Analytics, and Mendeley, for example).
These measures are not given as much credence as traditional metrics because a work could be viewed, downloaded and mentioned online but not used or cited in the scholarly literature. Altmetrics generally offer insights about the potential impact of a paper rather than the actual impact.