Citations indicate the use and dissemination of research findings, originally developed as an alternative to classification of subject areas.
Journal Citation Reports (JCR) is a product from Thomson Reuters that annually publishes Journal Impact Factors (JIF).
Journal Impact Factors (JIF) was a system conceived by Eugene Garfield in 1955 as a means of identifying journals for inclusion in Science Citation Index (SCI).
Some journal indexes order journals according to their 'quality', while other indexes function more as a directory.
Rankings use quantitative methods to indicate research quality. There are rankings for journals and universities, as well as for individual researchers.
Ulrichsweb is a global directory of journals offering an overview of accessible journals and their characteristics.