A citation index indexes the citations made in articles, linking the articles with the cited works.
Citation indexes are a powerful tool for literature search.
Citation indexes can be used to find related articles that may not be found using keywords. Citation indexes allow finding out where and how often an article is cited, allowing the estimation of the importance of an article. Citation statistics are widely used for the allocation of funds, promotion and tenure decisions, etc. Citation indexing for scientific articles was invented by Dr. Garfield, who founded the Institute for Scientific Information . One of the most popular citation indexes currently available is the Science Citation Index .