Scopus is Elsevier's abstract and citation database launched in 2004. Scopus covers nearly 36,377 titles (22,794 active titles and 13,583 inactive titles) from approximately 11,678 publishers, of which 34,346 are peer-reviewed journals in top-level subject fields: life sciences, social sciences, physical sciences and health sciences. It covers three types of sources: book series, journals, and trade journals. All journals covered in the Scopus database are reviewed for sufficiently high quality each year according to four types of numerical quality measure for each title; those are h-Index, CiteScore, SJR (SCImago Journal Rank) and SNIP (source normalized impact per paper). Scopus also also allows patent searches in a dedicated patent database Lexis-Nexis, albeit with a limited functionality.
Journals listed in Scopus are considered to be meeting the requirement for peer review quality established by several research grant agencies for their grant recipients and by degree accreditation boards in numerous countries.
Comparing ease of use and coverage of Scopus and the Web of Science (WOS), a 2006 study concluded that "Scopus is easy to navigate, even for the novice user. ... The ability to search both forward and backward from a particular citation would be very helpful to the researcher. The multidisciplinary aspect allows the researcher to easily search outside of his discipline" and "One advantage of WOS over Scopus is the depth of coverage, with the full WOS database going back to 1945 and Scopus going back to 1966. However, Scopus and WOS complement each other as neither resource is all-inclusive." Scopus provides more advanced structured query language capabilities, than Web of Science: for example, WoS can perform only NEAR/n queries, Scopus can also do PRE/n queries.
Also, when the same article is covered in Scopus and in the Web of Science (WoS), its Scopus coverage has a 2-4 larger number of keywords than its WoS coverage. This feature allows Scopus user to find a larger number of relevant publications.