Web of Science (WoS) is a selective citation index and research-information platform operated by Clarivate Analytics. It tracks articles in journals that meet defined quality and editorial standards, exposes citation links between them, and supports both literature search and impact analysis. WoS is not a “cover everything” archive; selectivity is part of its reputation. Inclusion in the WoS Core Collection is read by many institutions as a quality signal for journals and, by extension, for the papers they publish.
Inside the Core Collection, journals are grouped into major “leagues” by discipline and standing. SCIE covers science, engineering, and medicine; SSCI covers the social sciences; A&HCI covers arts and humanities. ESCI holds journals that meet quality thresholds but have not yet reached the citation impact typical of the higher tiers—an emerging layer rather than a dumping ground. That structure shapes answers to “which index?” in hiring, promotion, and funding files.
WoS data also feed Journal Citation Reports (JCR), where annual journal metrics such as Journal Impact Factor and quartiles are published. Scopus generally offers broader coverage; WoS offers a narrower, more selective core—substituting one for the other can mislead. In Turkey, appointment and associate-professorship juries often look specifically at WoS/JCR indexing and quartile. Related entries in this glossary unpack SCIE, SSCI, A&HCI, ESCI, and JCR as parts of the same family.
In practice you use WoS to ask both “where is this article indexed?” and “which league is this journal in?” Clarivate author profiles (ResearcherID) synced with ORCID help attach publications to the right person. On this site, the Find quartile tool and the journal catalog place WoS/JCR rows next to Scimago metrics for a side-by-side read.