RELX plc (pronounced "Rel-ex") is a British corporate group comprising companies that publish scientific, technical and medical material, and legal textbooks; provide decision-making tools; and organise exhibitions.

It operates in 40 countries and serves customers in over 180 nations. It was previously known as Reed Elsevier, and came into being in 1992 as a result of the merger of Reed International, a British trade book and magazine publisher, and Elsevier, a Netherlands-based scientific publisher. The company re-branded itself as RELX in February 2015.

RELX's Scientific, Technical & Medical business provides information, analytics and tools that help investors make decisions that improve scientific and healthcare outcomes. It operates under the name of Elsevier: ScienceDirect, an online database of primary research, contains 13 million documents.

Scopus is a bibliographic database containing abstracts and citations for academic journal articles. It contains more than 50 million items in more 20,000 titles from 5,000 publishers worldwide. Mendeley is a desktop and web program for managing and sharing research papers, discovering research data and collaborating online.

Elsevier is the world's largest publisher of academic articles. It publishes 420,000 articles a year in about 2,500 journals. Its best-known titles are The Lancet and Cell. 

RELX's exhibitions business is called Reed Exhibitions. It is the world's largest exhibitions company, running 500 shows for 140,000 exhibitors and 7m visitors.

According to en.wikipedia