Research impact has traditionally been described in terms of academic prestige and publication metrics. However it is increasingly being thought of as the societal benefits accruing from research.The Australian Research Council now defines research impact as:
...the contribution that research makes to the economy, society, environment or culture, beyond the contribution to academic research.
There is no single clear measure of impact. Various indices attempt to quantify scholarly impact using measures such as citations. Journals have impact factors, while altmetrics report on article usage. For ARC information on research impact see the file below.
Citation metrics measure the average citation count per article. They have their flaws, as many factors affect citation rates which have nothing to do with the quality of the research. The most well known is the H-index.
Article: Explainer: what is an H-index and how is it calculated? The Conversation 2015.
Journal impact ratings measure the impact and prestige of journals. However publishing in journals with high ompact factors may not guarantee the most relevant audience for a given piece of research.
Common journal ratings include:
Wikipedia - Journal rankings
Altmetrics measure output across a more diverse range of media including social media, online reference managers, page views etc.
Altmetric measures are commonly embedded in article pages.