Article-Level Metrics measure the "impact" or "reach" of an article in scholarly discourse. Whereas the well-known Impact Factor measures citations at a journal level, article-level metrics aim to measure the impact of individual articles. The best known article-level metric is the number of times an article has been cited. Other article metrics include:
PLoS has been the pioneer of many article level metrics and provide an excellent overview of the topic.
The Social Science Research Network (SSRN), a repository of social science articles, counts article downloads and provides lists of top articles, authors, and institutions based on the download counts.
Also, some Alternative Metrics track at the article level as well.
Citation tracking, or citation analysis, is an important tool used to trace scholarly research, measure impact, and inform tenure and funding decisions. The impact of an article is evaluated by counting the number of times an article is cited in others' work. Researchers do citation analysis for several reasons:
The output from citation studies is often the only way that non-specialists in governments and funding agencies, or even those in different scientific disciplines, can judge the importance of a piece of scientific research.
Here is a video by Taylor and Francis Group explaining what article-level metrics are and why they are important to researchers.
Web of Science is a comprehensive database that allows the user to not only see how many times an article has been cited in total, but also how any times it has been cited in the last 180 days.
Scopus provides the user with the number of times an article has been cited in the right hand column of the search results. Currently only works from 1996 to present are covered.
Public Library of Science (PLoS) is a nonprofit publisher that has spearheaded article metrics, allowing the user a broader range of metrics to inspect.
Social Science Research Network (SSRN) is a network that is focused on the dissemination of social science research. They employ a number of article metrics.
SSRN also offers a Top Papers page, to promote the top downloaded and cited articles in the database.
Google Scholar offers a vast breadth of research papers, some of which can be accessed thorough the University of Manitoba's "Get it@UML" button (access it through the link provided and that feature will work). Scholar offers its own article metrics.
Reviews and recommendations of articles are valuable to scholars. Some journals (like Computing Reviews) offer reviews of articles that appear in other journals. Journal clubs are popular because they allow a group to discuss an article in-depth. New social media networking tools allow readers to comment upon and rank articles.
PeerPub is a database of comments on articles. Users can find or introduce articles to the database, and share their comments on those articles.
Other publishers that allow users to comment and rate articles: