Definition · Plain-language
Web of Science
Web of Science is Clarivate’s curated citation index database — a selective "Core Collection" used for citation analysis and the source of the Journal Impact Factor through Journal Citation Reports.
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Origins and what it is
Web of Science grew out of citation-indexing pioneered by Eugene Garfield at the Institute for Scientific Information (ISI), beginning with the Science Citation Index in the 1960s. The core idea is to index not only articles but the references they cite, so that a user can follow links forward and backward through the literature — seeing both what a paper drew on and what later work cited it. Now owned by Clarivate, the platform brings together several indexes; its best-known component is the Core Collection, a selectively curated set of the journals, conference proceedings and books judged to meet quality criteria.
Citation analysis and identifiers
Because it captures cited references, Web of Science is a primary tool for citation analysis — counting citations, finding citing and cited works, and studying how research influence flows over time. It supports persistent author and output identifiers: ResearcherID (now integrated with the Web of Science author record, with publication verification handled through the platform formerly known as Publons) and publication-level records that help disambiguate authorship. These features let researchers maintain a verified profile of their outputs and citation record, complementing other persistent identifiers such as the ORCID iD.
Source of the Journal Impact Factor
The Journal Impact Factor is calculated from Web of Science citation data and published annually by Clarivate in the Journal Citation Reports (JCR). Only journals indexed in the Core Collection receive an impact factor, which is one reason Core Collection inclusion carries weight in scholarly publishing. Web of Science data also feed related indicators such as the Eigenfactor and Journal Citation Indicator. Because the impact factor is widely misapplied to individual researchers, responsible-assessment frameworks such as DORA caution against using journal-level metrics derived from any single database to judge individual work.
Web of Science compared with Scopus
Web of Science (Clarivate) and Scopus (Elsevier) are the two dominant curated, subscription citation databases, and both are selective rather than comprehensive. Web of Science’s Core Collection is valued for its long historical depth and is the source of the Journal Impact Factor, while Scopus generally indexes a larger number of journals, particularly in the social sciences and humanities. Both differ from free, automatically harvested indexes such as Google Scholar, which offer wider but less quality-controlled coverage. For systematic reviews, searching more than one database is standard practice to reduce the risk of missing relevant literature.
Key facts
At a glance
- Definition: Clarivate’s curated citation index database
- Owner: Clarivate (originally ISI; founder Eugene Garfield)
- Core part: the selectively curated Web of Science Core Collection
- Flagship metric: source of the Journal Impact Factor via Journal Citation Reports
- Identifiers: ResearcherID / Publons author and publication records
- Compare: Scopus (Elsevier) — overlapping but distinct coverage
Common misconceptions
What people often get wrong
Often heard: Web of Science indexes every scholarly journal that exists.
Actually: No — its Core Collection is selectively curated against quality criteria, so many journals are not indexed. This selectivity is deliberate and underpins its use in citation analysis and the Journal Impact Factor.
Often heard: Web of Science and Scopus are interchangeable and contain the same records.
Actually: Their coverage overlaps but differs in scale and emphasis. Web of Science is noted for historical citation depth; Scopus generally indexes more titles. Methodologists recommend searching both for systematic reviews.
Often heard: Being indexed in Web of Science means a journal’s articles are high quality individually.
Actually: Indexing is a journal-level judgement and the impact factor is a journal-level metric. Neither certifies the quality of an individual article — DORA advises assessing articles on their own merits.
Going deeper
