Citation analysis measures an article's impact based on the number of times it has been cited. It is the examination of the frequency, patterns, and graphs of citations in articles and books. It uses citations in scholarly works to establish links to other works or other researchers. In many databases, you can find this metric by clicking on their "Cited By" links for a particular article.
Altmetrics, which stands for "alternative metrics," measure research's impact using new sources of data based on online activity, such as Likes, Tweets, and Shares. These metrics compliment but do not replace traditional metrics, like citation analysis. The advantages of using Altmetrics are that they can provide instant feedback, can be applied to all forms of scholarly output (articles, books, data, software, etc.), and can measure diverse impacts of research. Some examples of Altmetrics tools are: