Academic journals are often ranked according to their influence and impact. These rankings include metrics such as impact factors calculated from citation data. Not all high impact articles are referenced frequently so for this reason impact factors and other metrics should always be viewed in context. They are intended as a guideline within a discipline, not as a numeric value to be taken in isolation. Some researchers use impact factors to decide which journals they will use for research purposes and which journals they will submit their articles to for publication.
Journal impact factors were created by Eugene Garfield to enable researchers to assess the impact of scholarly journals. They were also used by authors who wished to publish in high academic prestige journals.
There are numerous resources currently available to measure the impact of scholarly journals.
Google Scholar Metrics state that they
provide an easy way for authors to quickly gauge the visibility and influence of recent articles in scholarly publications. Scholar Metrics summarise recent citations to many publications, to help authors as they consider where to publish their new research.
To get started, you can browse the top 100 publications in several languages, ordered by their five-year h-index and h-median metrics. To see which articles in a publication were cited the most and who cited them, click on its h-index number to view the articles as well as the citations underlying the metrics.
IEEE provide citation impact information including ranking papers by most cited.