Helsinki is the capital and largest city in Finland. It is in the region of Uusimaa, located in southern Finland, on the shore of the Gulf of Finland, an arm of the Baltic Sea. The population of the city of Helsinki is 588,941 (31 January 2011), making it by far the most populous municipality in Finland. Helsinki is located some 400 kilometres (250 mi) east of Stockholm, Sweden, 300 kilometres (190 mi) west of St. Petersburg, Russia and 80 kilometres (50 mi) north of Tallinn, Estonia. Helsinki has close historical connections with these three cities.

The Helsinki Metropolitan Area includes the city of Helsinki and three other cities: Espoo and Vantaa, which immediately border Helsinki to the west and north, respectively; and Kauniainen, which is an enclave within the city of Espoo. The Helsinki metropolitan area is the world's northernmost urban area among those with a population of over one million people, and the city is the northernmost capital of a EU member state. Altogether 1.1 million people, approximately one in five Finns, live in the Helsinki Metropolitan Area.

Helsinki is Finland's major political, educational, financial, cultural and research centre as well as one of northern Europe's major cities. Approximately 70% of foreign companies operating in Finland have settled in the Helsinki region.

The nearby city of Vantaa in the Helsinki metropolitan area is the location of Helsinki-Vantaa Airport, with frequent service to various destinations in Europe and Asia. Since early 2009, Helsinki has been exploring a merger with Vantaa. On 30 March 2009, the city council of Vantaa agreed to review Helsinki's proposal of a possible merger, while emphasizing that the review is not about the possibility of terminating the existence of the city of Vantaa. On 31 January 2011, the city council of Vantaa turned down Helsinki's proposal of a possible merger, with 45 votes against the proposal compared to 22 in favour of it.
In 2009, Helsinki was chosen to be the World Design Capital for 2012 by the International Council of Societies of Industrial Design. Helsinki narrowly beat out Eindhoven for the title.

The Swedish name Helsingfors is the original official name of the city of Helsinki (in the very beginning, spelled Hellssingeforss). The Finnish language form of the name probably originates from Helsinga and similar names used for the river that is currently known as the Vantaa River as documented already in the 14th century. Helsinki (pronounced with the stress on the first syllable: Finnish pronunciation: [ˈhelsiŋki]), is used to refer to the city in all languages except Swedish, Norwegian and Danish. Helsingfors comes from the name of the surrounding parish, Helsinge (source for Finnish Helsinki) and the rapids (Swedish: fors), which flowed through the original village. The name Helsinge may have originated with medieval Swedish settlers who came from Hälsingland in Sweden. Others have proposed that the name derives from the Swedish word hals (neck), referring to the narrowest part of the river, i.e. the rapids.
In Helsinki slang the city is known as Stadi (from the Swedish word stad, meaning "city"). Elsewhere in Finland, in colloquial Finnish its nickname is Hesa. Helsset is the Northern Saami name of Helsinki.

Helsinki is spread across a number of bays and peninsulas and over a number of islands. The inner city area occupies a southern peninsula, which is rarely referred to by its actual name Vironniemi. Population density in certain parts of Helsinki's inner city area is very high, reaching 16,494 inhabitants per square kilometre (42,720 /sq mi) in the district of Kallio, but as a whole Helsinki's population density of 3,050 per square kilometre (7,900 /sq mi) ranks it as quite sparsely populated in comparison to other European capital cities. Much of Helsinki outside the inner city area consists of postwar suburbs separated from each other by patches of forest. A narrow, ten-kilometre-long (6 mi) Helsinki Central Park that stretches from the inner city to the northern border of Helsinki is an important recreational area for residents.
Major islands in Helsinki include Seurasaari, Lauttasaari and Korkeasaari – the latter being the site of the country's biggest zoo. Other significant islands are the fortress island of Suomenlinna (Sveaborg) and the military island of Santahamina. Pihlajasaari island is a favourite summer spot for gay men and naturists, very much comparable to Fire Island off New York City.

Carl Ludvig Engel (1778–1840) was appointed to design a new city centre all on his own. He designed several neoclassical buildings in Helsinki. The focal point of Engel's city plan is the Senate Square. It is surrounded by the Government Palace (to the east), the main building of the University (to the west), and (to the north) the enormous Cathedral, which was finished in 1852, twelve years after C. L. Engel's death. Subsequently, Engel's neoclassical plan stimulated the epithet, The White City Of The North. Helsinki is, however, perhaps even more famous for its numerous Art Nouveau (Jugend in Finnish) buildings, designed in the early 1900s and strongly influenced by the Kalevala, which is a very popular theme in the national romantic art of that era. Helsinki's Art Nouveau style is also featured in large residential areas such as Katajanokka and Ullanlinna. The master of the Finnish Art Nouveau was Eliel Saarinen (1873–1950), whose architectural masterpiece was the Helsinki central railway station.

Helsinki also features several buildings by the world-renowned Finnish architect Alvar Aalto (1898–1976), recognized as one of the pioneers of architectural functionalism. However, some of his works, such as the headquarters of the paper company Stora Enso and the concert venue, Finlandia Hall, have been subject to divided opinions from the citizens.

Renowned functionalist buildings in Helsinki by other architects include the Olympic Stadium, the Tennis Palace, the Rowing Stadium, the Swimming Stadium, the Velodrome, the Glass Palace, the Exhibition Hall (now Töölö Sports Hall) and Helsinki-Malmi Airport. The sports venues were built to serve the 1940 Helsinki Olympic Games; the games were initially cancelled due to the Second World War, but the venues eventually got to fulfill their purpose in the 1952 Olympic Games. Many of them are listed by DoCoMoMo as significant examples of modern architecture. The Olympic Stadium and Helsinki-Malmi Airport are in addition catalogued by the National Board of Antiquities as cultural-historical environments of national significance.
As a historical footnote, Helsinki's neoclassical buildings were often used as a backdrop for scenes set to take place in the Soviet Union in many Cold War era Hollywood movies, when filming in the USSR was not possible. Some of the more notable ones are The Kremlin Letter (1970), Reds (1981) and Gorky Park (1983). Because some streetscapes were reminiscent of Leningrad's and Moscow's old buildings, they too were used in movie productions—much to some residents' dismay. At the same time the government secretly instructed Finnish officials not to extend assistance to such film projects.

Finnish and Swedish are the official languages of the municipality of Helsinki. The majority, or 84.3% of the population, speak Finnish as their native language. A minority, at 6.1%, speak Swedish. Around 9.6% of the population speak a native language other than Finnish or Swedish. Helsinki slang combines influences from both Finnish, Swedish and Russian languages. While Swedish was historically the majority spoken language of the city (prior to 1890), Finnish today is the common language of communication between Finnish speakers, Swedish speakers and speakers of other languages (new Finns) in day-to-day affairs in the public sphere between unknown persons. In case a speaker's knowledge of Finnish is not known, English is usually spoken. Swedish is commonly spoken in city agencies specifically aimed at Swedish speakers, such as the Social Services Department on Hämeentie or the Luckan Cultural centre in Kamppi. Knowledge of Finnish is also essential in business and is usually a basic requirement in the employment market.
Finnish speakers surpassed Swedish speakers in 1890 to become the majority of the city's population. At the time, Helsinki's population was 61,530.

The biggest historical museum in Helsinki is the National Museum of Finland, which displays a vast historical collection from prehistoric times to the 21st century. The museum building itself, a national romantic style neomedieval castle, is a tourist attraction. Other major historical museum is the Helsinki City Museum, which introduces visitors to Helsinki's 500 year history. The University of Helsinki also has many significant museums, including the University Museum and the Natural History Museum.
The Finnish National Gallery consists of three museums: Ateneum Art Museum for classical Finnish art, Sinebrychoff Art Museum for classical European art, and Kiasma Art Museum for modern art. The old Ateneum, a neo-Renaissance palace from 19th century, is one of the city's major historical buildings. All three museum buildings are state-owned through Senate Properties.
Helsinki has three major theatres: The Finnish National Theatre, the Helsinki City Theatre, and the Finland Swedish Svenska Teatern. The city's main musical venues are the Finnish National Opera and the Finlandia concert-hall. Bigger concerts and events are usually held at one of the city's two big ice hockey arenas: the Hartwall Areena or the Helsinki Ice Hall. Helsinki has Finland's largest fairgrounds.
Many widely renowned and acclaimed bands have originated in Helsinki, including Hanoi Rocks, HIM, Stratovarius, The 69 Eyes, Norther, Wintersun, Finntroll, Ensiferum, The Rasmus and Apocalyptica.

Roads
The backbone of Helsinki's motorway network consists of three semicircular ring roads, Ring I, Ring II, and Ring III, which connect together expressways heading to other parts of Finland, and the western and eastern arteries of Länsiväylä and Itäväylä respectively. While variants of a Keskustatunneli tunnel under the city centre have been repeatedly proposed, as of 2011 the plan remains on the drawing board.
Helsinki has some 390 cars per 1000 inhabitants. This is less than in cities of similar density, for instance, Brussels' 483 per 1000 and Stockholm's 401, and Oslo's 413.

Rail transport and buses
Public transportation is generally a hotly debated subject in the local politics of Helsinki. In Helsinki metropolitan area, public transportation is managed under Helsinki Region Transport, the metropolitan area transportation authority. The diverse public transport system consists of trams, commuter rail, the subway, bus lines and two ferry lines.

Today, Helsinki is the only city in Finland to have trams or subway trains. There used to be two other cities in Finland with trams: Turku and Viipuri (Vyborg, now in Russia), but both have since abandoned trams. The Helsinki Metro, opened in the year 1982, is the only subway system in Finland. In 2006, the construction of the long debated extension of the subway system west into Espoo was approved, and serious debate about an eastern extension into Sipoo has taken place.
The possibility of a Helsinki to Tallinn Tunnel is currently being researched. The rail tunnel would connect Helsinki to the Estonian capital Tallinn, further linking Helsinki to the rest of continental Europe by Rail Baltica.

Aviation
Air traffic is handled primarily from the international Helsinki Airport, located approximately 19 kilometres (12 mi) north of Helsinki's downtown area, in the neighbouring city of Vantaa. Helsinki's second airport, Malmi Airport, is mainly used for general and private aviation. Copterline has provided fast (18 min.) helicopter flights to Tallinn, but discontinued the regular service in December 2008 on grounds of unprofitability.

Sea transport
Ferry connections to Tallinn, Mariehamn and Stockholm are serviced by various companies. Finnlines passenger-freight ferries to Gdynia, Poland, Travemünde, Germany and Rostock, Germany are also available. St Peter Line offers passenger ferry service to Saint Petersburg several times a week.