Bærum (Norwegian:  ⓘ) is a municipality in the Greater Oslo Region in Norway that forms an affluent suburb of Oslo on the west coast of the city. Bærum is Norway's fifth largest municipality with a population of 128,760 (2021). It is part of the electoral district and historical county of Akershus and of the newer Viken County. The administrative centre of the municipality is the town of Sandvika.  Bærum was established as a municipality on 1 January 1838.
 Bærum has the highest income per capita in Norway and the highest proportion of university-educated individuals. Bærum, particularly its eastern neighbourhoods bordering West End Oslo, is one of Norway's priciest and most fashionable residential areas, leading Bærum residents to be frequently stereotyped as snobs in Norwegian popular culture. The municipality has been voted the best Norwegian place to live in considering governance and public services to citizens.
 The name (Old Norse: Bergheimr) is composed of berg, which means "mountain", and heimr, which means "homestead" or "farm". It probably originally belonged to a farm located at the base of the prominent mountain of Kolsås. In Old Norse times, the municipality was often called Bergheimsherað, meaning "the herað (parish/district) of Bergheimr".
 The coat-of-arms was granted on 9 January 1976. They show an old silver-colored lime kiln on a green background. That was an important aspect of the local economy from the Middle Ages until around 1800. There are still some original ovens visible in the municipality.
 The area known today as Bærum was a fertile agricultural area as far back as the Bronze Age, and several archeological finds stem from the Iron Age.  The first mention of the name is from the saga of Sverre of Norway, from about 1200.  There are ruins of stone churches from the 12th century at Haslum and Tanum.
 The pilgrim road to Trondheim that was established after 1030 went through Bærum, and there is evidence that lime kilns were in use in the area in 850.  There were shipping ports for the quicklime at Slependen and Sandvika.  The lime kiln is the main motif for the municipality's coat of arms.
 In the 17th century, iron ore was discovered in Bærum and the ironworks at Bærums Verk were founded.  Industries such as paper mills, nail factories, sawmills, glassworks, and brickworks were established along the rivers Lysakerelven and Sandvikselva in the following centuries.  There were orchards and other agricultural concerns throughout the area, remnants of which still exist today.
 A number of artists established themselves in Bærum, particularly around the art school run by Johan Fredrik Eckersberg.  Among the artists who did much of their work in Bærum are Frits Thaulow, Christian Skredsvig, Harriet Backer, Kitty Lange Kielland, Otto Sinding, Eilif Pettersen, Gerhardt Munthe, and Erik Werenskiold.
 Starting in the mid-20th century, Bærum's agricultural base gradually gave way to residential construction.  Still, only a third of the area, 64 square kilometres (24.7 sq mi), is built up for residential use; over half is productive forestry; and nearly 17 square kilometres (6.6 sq mi) is still agricultural.
 In 2010, that year's Eurovision Song Contest was hosted in Bærum.
 On 10 August 2019, a gunman opened fire on congregants at the Al-Noor Islamic Centre.
 The physical geography of Bærum is dominated by a craggy coastline along the Oslofjord and inland, hilly areas rising to the north and east, where there are large forested areas.  The mountain of Kolsås forms a natural center, but the municipality also includes the secluded valley of Lommedalen.  Four major rivers flow through the municipality: Lysakerelven, Sandvikselva, Lomma, and Øverlandselva, and there are numerous lakes, both in residential and forested areas. The official municipality flower is Anemone ranunculoides.
 The geology of Bærum is part of the Oslo Graben and includes Rhomb porphyry at Kolsås.
 Since nearly two-thirds of Bærum's area consists of forests, there are rich opportunities for outdoor activities, such as skiing, hiking, and fishing. The forests are considered part of Marka, the forested areas in and around Greater Oslo. Areas within the municipality of Bærum include Bærumsmarka, Vestmarka, and Krokskogen.
 The highest point in Bærum is Vidvangshøgda at 60°01′27″N 10°29′02″E﻿ / ﻿60.0242329°N 10.4838324°E﻿ / 60.0242329; 10.4838324 with an altitude of 552 metres (1,811 ft). The largest lake is Stovivatnet with an area of 0.420 square kilometres (0.162 sq mi) at 59°54′28″N 10°27′03″E﻿ / ﻿59.9078776°N 10.4508305°E﻿ / 59.9078776; 10.4508305
 Bærum's industrial base has since the 1950s given way to service industries, including retailing, engineering, public services, etc.  It derives much of its tax base by being a bedroom community to Oslo.  It is one of the most affluent areas in Norway.
 Two of Norway's busiest highways (E18 and E16) and one railroad traverse the municipality.  There has been considerable development of office parks along E18, especially around Lysaker in the last 20–30 years, reducing some of the pressure on downtown areas of Oslo.
Scandinavian Airlines System Norway has its offices in Fornebu, Bærum. The airline Widerøe has some administrative offices in Lysaker, Bærum. Norwegian Air Shuttle has its head office in Fornebu.
 Partnair, a charter airline, was headquartered at Fornebu Airport. When the airline Busy Bee of Norway existed, its head office was on the grounds of Fornebu Airport. Braathens and SAS Braathens had their head office facilities in a building on the grounds of Fornebu Airport. In 2010, Norwegian Air Shuttle bought the former Braathens head office.
 Bærum (2009) is the fifth most densely populated municipality in Norway.  Along the E18 highway, the residential area is continuous with Oslo and continues with some interruption through to the neighboring municipality of Asker.
 Bærum is also the most affluent of Norwegian municipalities, with average per capita income (2002 figures) of NOK 370,800; compared with the national average of NOK 262,800.  It also has the highest level of education nationwide.
 Administratively, Bærum is divided into 22 sections. The population for each section on 1 January 2005 was:
 According to a local survey conducted by Dagbladet, Bærum is the best place to live in Norway in terms of governance and services to residents.  In addition is it also one of the best places for young people to grow up. Bærum score high on national surveys when it comes to local economical governance, education and possibilities for young people, health coverage, school rankings, and work rights and possibilities
 There are a number of schools in Bærum, both public and private. There are a total of 43 public elementary schools ( primary and / or secondary ) and some private, including Bærum Montessori School. According to national surveys, Jar public elementary school ranks the highest when it comes to math, while Lommedalen public elementary school ranks the highest in reading, both are located in Bærum.
 There are eight public high schools in Bærum; Dønski, Eikeli, Nadderud, Rosenvilde, Rud, Sandvika, Stabekk and Valler. In addition, the Norwegian College of Elite Sport and Steiner School. The Folk University also has a branch in Sandvika. Valler High School has been ranked within the top 5 high schools in Norway for several years, while Nadderud High School ranks within the top 20. In the later years both schools have met competition from the newly established Sandvika High School. Sandvika High School has had the highest number of applications in the county for the past six years, and is now ranked within top 10 in the country. In 2013 the school also won for Best Entrepreneurship School in Norway.
 Stabæk IF plays in Eliteserien, the highest division for men's football in Norway. Bærum SK
plays in the 2. divisjon, the third highest division of the Norwegian football league system.
 Stabæk IF's women's football team, Stabæk Fotball Kvinner, plays in Toppserien, the Norwegian top division.
 Høvik IF and Stabæk IF plays in the highest bandy division and Hauger BK in the second highest.
 The following cities are twinned with Bærum: