RELX Group (known as Reed Elsevier between 1992 and February 2015) is a multinational information and analytics company based in London, in the United Kingdom. It operates in four market segments: scientific, technical and medical; risk and business information; legal; and exhibitions. It is a dual-listed company. RELX PLC, the London Stock Exchange listed shareholding vehicle, holds 52.9% of the shares in RELX Group. RELX NV, the Amsterdam Stock Exchange listed shareholding vehicle, holds 47.1% of the shares in RELX Group. The shares are traded on the London Stock Exchange, Amsterdam Stock Exchange and New York Stock Exchange using the following ticker symbols: London: REL, Amsterdam: REN, New York: RELX and RENX. The company is one of the constituents of the FTSE 100 Index, Financial Times Global 500 and Euronext 100 Index. The company operates in 38 countries and serves customers in over 180 nations.  About 50% the company’s revenues are generated from the US, with 29 per cent from Europe and 21 per cent from the rest of the world.In 2000, two-thirds of revenues were from print and only a small percentage was digital. By 2015, those numbers had been reversed. Print now generates just 14 per cent of revenues at RELX Group.  7,000 of RELX Group’s 28,000 employees are technologists and about 95 per cent of the company’s €500m capital spending is on technology. High Performance Computing Cluster technology is crucial to the company’s strategy. 
In 1965 Reed Group, as it was then known, became a conglomerate, creating its Decorative Products Division with the purchase of Crown Paints, Polycell and Sanderson's wallpaper and DIY decorating interests.
In 1970, Reed Group merged with the International Publishing Corporation and the company name was changed to Reed International Limited. The company continued to grow by merging with other publishers and produced high quality trade journals as IPC Business Press Ltd and women's and other consumer magazines as IPC magazines Ltd. The original family owners, the Reeds, were Methodists and encouraged good working conditions for their staff in the then-dangerous print trade.
In 1880, Jacobus George Robbers started a publishing company called NV Uitgeversmaatschappij Elsevier (Elsevier Publishing Company NV) to publish literary classics and the encyclopedia Winkler Prins. Robbers named the company after the old Dutch printers family Elzevir, which, for example, published the works of Erasmus in 1587. Elsevier NV originally was based in Rotterdam but moved to Amsterdam in the late 1880s.
Up to the 1930s, Elsevier remained a small family-owned publisher, with no more than ten employees. After the war it launched the weekly Elsevier magazine, which turned out to be very profitable. A rapid expansion followed. Elsevier Press Inc. started in 1951 in Houston, Texas, USA, and in 1962 publishing offices were opened in London and New York. Multiple mergers in the 1970s led to name changes, settling at "Elsevier Scientific Publishers" in 1979. In 1991, two years before the merger with Reed, Elsevier acquired Pergamon Press in the UK.
The company bought the Official Airline Guides Inc, a publisher of airline schedules, for $425 million in August 1993, LexisNexis, an on-line information business, for $1.5 billion in October 1994 and MDL Information Systems Inc, a US software systems and information database developer, for $320 million in March 1997.
The company then acquired Chilton Business Group, a US business information publishing company, for $447 million in June 1997, Matthew Bender & Company Inc, a US publisher of legal information, for $1.65 billion in April 1998 and Harcourt, an education publishing business, for US$4.5 billion plus debt in October 2000.
In 2004, LexisNexis acquired Seisint of Boca Raton, Florida, which provided the company with access to HPCC Systems for the first time and in May 2005 it bought Medimedia, a medical publisher, for $270 million.
In February 2008, shareholders of Choicepoint voted in favor of acquisition by the company for $4.1 billion. Choicepoint was an American data aggregation company. The acquisition was completed in September 2008.
In June 2011, Reed Business Information, a RELX Group business, acquired Ascend, a London-based civil aviation data analytics company.
In November 2011 Reed Elsevier purchased US online-data business Accuity Holdings Inc. from investment firm Investcorp for £343 million ($530.1 million) in cash.
In March 2012, LexisNexis Legal & Professional, a RELX Group company, acquired Law360, a US-based online provider of legal information and analysis.
In April 2013, Elsevier, a RELX Group company, acquired Mendeley, a London-based desktop and web program for managing and sharing research papers, discovering research data and collaborating online.
In September 2013, LexisNexis Risk Solutions, a RELX Group company, acquired Mapflow, a Dublin-based group that helps insurance companies assess geographic risk, in particular in relation to flooding.
In April 2014, LexisNexis Risk Solutions acquired Tracesmart, a UK-based provider of tracing, identity verification, fraud prevention and anti-money laundering solutions.
In May 2014, LexisNexis Risk Solutions acquired Wunelli, a telematics data business which uses driving data for insurers, enabling them to reduce risk exposure and deliver discounts to safer drivers.
In September 2014, Accuity, a RELX business, acquired Fircosoft, a Paris-based anti-money laundering company.
In November 2014, LexisNexis Risk Solutions bought Health Market Science, a supplier of high quality data about US healthcare professionals.
In January 2015, LexisNexis Risk Solutions acquired BAIR Analytics, a US-based law enforcement data company.
In November 2015, LexisNexis Legal & Professional, a RELX Group company, acquired Lex Machina, a US-based online provider of legal analytics.
In February 2007, the company announced its intention to sell Harcourt, its educational publishing division. On 4 May 2007 Pearson, the international education and information company, announced that it had agreed to acquire Harcourt Assessment and Harcourt Education International from Reed Elsevier for $950m in cash. In July 2007, Reed Elsevier announced its agreement to sell the remaining Harcourt Education business, including international imprint Heinemann, to Houghton Mifflin Riverdeep Group for $4 billion in cash and stock.
In April 2010, Reed Elsevier announced that it had sold 21 US magazines to other owners in recent months, and that an additional 23 US trade magazines, including Restaurants & Institutions, Hotels, and Trade Show Week would cease publication. The closures were mostly due to the weak economy including an advertising slump.
Variety, the company’s last remaining North American title, was sold in October 2012.
In 2014, Reed Business Information sold BuyerZone, an online marketplace; emedia, an American provider of research for IT buyers and vendors; and a majority stake in Reed Construction Data, a provider of construction data.
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 with 16 per cent market share, according to the Financial Times. It publishes 380,000 articles a year in about 2,500 journals. Its best-known titles are The Lancet and Cell. In 1995, Forbes Magazine (wrongly) predicted Elsevier would be “the first victim of the internet” as it was disrupted and disintermediated by the world wide web. Elsevier had annual sales of £2bn (€2.8bn) in 2014.
Elsevier has been criticized for its high prices; excessive profitability; and limiting the diffusion of innovation by putting scientific research behind paywalls.
The business claims to have saved the state of Florida more than $60 million a year by preventing benefit fraud. Leading brands include Flightglobal, Farmers Weekly, Elsevier magazine and New Scientist. In 2015, Forbes Magazine voted LexisNexis, a RELX Group company, one of the top 10 employers in the US Technology Sector.
Since 2000, LexisNexis Risk Solutions technology has helped trace 149 missing children through its ADAM Programme. 
RELX Group’s legal business operates under the LexisNexis brand. Many of LexisNexis’ brands date back to the nineteenth century or earlier. These include Butterworths and Tolley in the UK and JurisClasseur in France.
RELX Group’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..
In January 2013, shortly after the Sandy Hook Elementary School Shooting when 20 children and six adult staff members were killed, Reed Exhibitions caused an uproar at the Eastern Sports and Outdoor Show when it decided to not allow assault weapons and high-capacity magazines at the show, also known as AR-15s. This decision caused a huge backlash and subsequent boycott that eventually shut the show down for that year. Also the National Shooting Sports Foundation (NSSF) terminated their management of the SHOT show held in Las Vegas every year.
In 2007, Reed Exhibitions sold its defense exhibitions business.
The Reed Elsevier Environmental Challenge awards grants to projects advancing access to safe water and sanitation.
The Elsevier Foundation supports libraries in developing countries, women scientists and nursing facilities.
LexisNexis Legal & Professional has worked with the Atlantic Council to launch the first draft of the Global Rule of Law Business Principles which will help businesses, law firms and NGOs promote and uphold the rule of law.
LexisNexis Legal & Professional has worked with the International Bar Association to launch an application called eyeWitness to Atrocities. The app is designed to capture GPS coordinates, date and time stamps, sensory and movement data, and the location of nearby objects such as Wi-Fi networks. The technology also creates a secure chain of custody to help verify that the images and video has not been edited or digitally manipulated. The goal is to create content that can be used in a court of law to prosecute perpetrators of atrocities and human rights abuses.
LexisNexis Risk Solutions continues to operate the ADAM (Automated Delivery of Alerts on Missing Children) programme in the US, developed by employees. The programme assists in the recovery of missing children through its system of targeted alerts. LexisNexis Risk Solutions has also launched Social Media Monitor to help law enforcement officials investigate serious crimes such as drug dealing and human trafficking.
In 2016 Elsevier's not-for-profit Elsevier Foundation committed $1m a year, for 3 years, to programmes encouraging diversity in science, technology and medicine and promoting science research in developing countries.
Reed Elsevier has been criticised for the high prices of its journals and services, especially those published by Elsevier. It has also supported SOPA, PIPA and the Research Works Act, although it no longer supports the last. Because of this, members of the scientific community have boycotted Elsevier journals. In January 2012, the boycott gained an online pledge and petition (The Cost of Knowledge) initiated by mathematician and Fields medalist Sir Timothy Gowers. The movement has received support from noted science bloggers, such as biologist Jonathan Eisen. Between 2012 and November 2015, about 15,391 scientists signed The Cost of Knowledge boycott. In 2014, Elsevier received article submissions from 1.8m authors.
Reed Elsevier collected, used, and sold data on millions of consumers. It has settled a Federal Trade Commission action taken against it, for failure to provide reasonable security for a database containing names, current and prior addresses, dates of birth, drivers license numbers and Social Security numbers, amongst other data. This information was obtained from credit reporting agencies and other sources, and made available to purchasers through a password-secured website which permitted easy-to-guess passwords, allowing identity thieves to steal records on over quarter of a million people. This breach occurred in 2008 through a recently purchased subsidiary, Seisint.
Between 2005 and 2007, members of the medical and scientific communities, which purchase and use many journals published by Reed Elsevier, agitated for the company to cut its links to the arms trade. Two UK academics, Dr Tom Stafford of Sheffield University and Dr Nick Gill, launched petitions calling on Reed Elsevier to stop organising arms fairs. A subsidiary, Spearhead, organised defence shows, including an event where it was reported that cluster bombs and extremely powerful riot control equipment were offered for sale.