Colombo is the commercial capital and largest city of Sri Lanka by population. According to the Brookings Institution, Colombo metropolitan area has a population of 5.6 million, and 752,993 in the city proper. It is the financial centre of the island and a tourist destination. It is located on the west coast of the island and adjacent to the Greater Colombo area which includes Sri Jayawardenepura Kotte, the legislative capital of Sri Lanka and Dehiwala-Mount Lavinia. It is also the administrative capital of the Western Province and the district capital of Colombo District. Colombo is a busy and vibrant place with a mixture of modern life and colonial buildings and ruins.Due to its large harbour and its strategic position along the East–West sea trade routes, Colombo was known to ancient traders 2,000 years ago. It was made the capital of the island when Sri Lanka was ceded to the British Empire in 1815, and its status as capital was retained when the nation became independent in 1948. In 1978, when administrative functions were moved to Sri Jayawardenepura Kotte, Colombo was designated as the commercial capital of Sri Lanka. It has one of the largest artificial harbours in the world and handles the majority of Sri Lanka’s foreign trade.

Like many cities, Colombo's urban area extends well beyond the boundaries of a single local authority, ] encompassing other municipal and urban councils such as Sri Jayawardenepura Kotte Municipal Council, Dehiwala Mount Lavinia Municipal Council, Kolonnawa Urban Council, Kaduwela Municipal Council and Kotikawatte Mulleriyawa Pradeshiya Sabha. The main city is home to a majority of Sri Lanka's corporate offices, restaurants and entertainment venues.
 

• Colombo city proper has a population estimated at 707,000 people for 2015. Within city limits, there is a land area measuring 14.4 square miles (37.3 square kilometers)
   
• Since ancient times, Sri Lanka was known for its cinnamon. The country still produces 80 to 90 percent of the world supply of C.verum cinnamon
  Two Guinness World Records were achieved in front of an enthusiastic crowd inside one of Colombo’s public parks on December 22, 2011. Sri Lankan Sanath Bandara put on 257 T-shirts the most ever and within the minimum time
   
• Sri Lanka exported US$10.5 billion worth of products around the globe in 2016, according to the estimates from the International Trade Centre
   

Colombo is a charter city, with a mayor-council government. The mayor and council members are elected through local government elections held once in five years. For the past 50 years the city had been ruled by the United National Party (UNP), a right leaning party, whose business friendly policies resonate with the population of Colombo. However the UNP nomination list for the 2006 Municipal elections was rejected, and an Independent Group supported by the UNP won the elections. Uvais Mohamed Imitiyas was subsequently appointed Mayor of Colombo.The city government provides sewer, road management and waste management services, in case of water, electricity and telephone utility services the council liaises with the water supply and drainage board, the Ceylon electricity board and telephone service providers. Colombo was the capital of the coastal areas controlled by the Portuguese, the Dutch and the British from the 1700s to 1815 when the British gained control of the entire island following the Kandian convention. From then until the 1980s the national capital of the island was Colombo. During the 1980s plans were made to move the administrative capital to Sri Jayawardenepura Kotte and thus move all governmental institutions out of Colombo to make way for commercial activities. As a primary step, the Parliament was moved to a new complex in Kotte and several ministries and departments were also moved. However, the move was never completed. Today many governmental institutions still remain in Colombo. These include the President's House, Presidential Secretariat, Prime Minister's House (Temple Trees), Prime Minister's Office, the Supreme Court of Sri Lanka, Central Bank of Sri Lanka, important government ministries and departments; such as Finance (Treasury), Defence, Public Administration & Home affairs, Foreign affairs, Justice and the Military headquarters, Naval headquarters (SLNS Parakrama), Air Force headquarters (SLAF Colombo) and Police national and field force headquarters.

The great majority of Sri Lankan corporations have their head offices in Colombo including Aitken Spence, Ceylinco Corporation, Stassen group of companies, John Keells Holdings, Cargills, Hemas Holdings, and Akbar Brothers. Some of the industries include chemicals, textiles, glass, cement, leather goods, furniture, and jewellery. In the city centre is the World Trade Centre. The 40-story Twin Tower complex is the centre of important commercial establishments, in the Fort district, the city's nerve center. Right outside the Fort area is Pettah which is derived from the Sinhala word pita which means 'out' or 'outside'.The Colombo Metropolitan area has a GDP of $122 billion or 40% of the GDP, making it the most important aspect of the Sri Lankan economy.The per capita income of Colombo Metro area stood at US$8623 and purchasing power per capita of $25,117, making it one of the most prosperous regions in South Asia. The Western province contributes less than 40% to the GDP and about 80% of industrial value additions although it accounts for only 5.7% of the country's geographic area and 25% of the national population. Given its importance as the primary international gateway for Sri Lanka and as the main economic driver of the country, the government of Sri Lanka has launched an ambitious program to transform Colombo and its area into a metropolis of international standards. Bottlenecks are preventing the Colombo metropolitan area from realizing its full economic potential. To facilitate the transformation of Colombo, the government has to address these bottlenecks which have for long been obstructing economic and physical urban regeneration.Pettah is more crowded than the Fort area. Pettah's roads are always packed and pavements are full of small stalls selling items from delicious sharbat to shirts. Most of these businesses are dominated by Muslim traders. At the end of the Main Street further away from Fort is the Sea Street – Sri Lanka's gold market – dominated by Tamil interests. This mile-long street is full of jewellery shops,including the former head office of SriLankan Airlines.

The city’s manufacturing industries are based on the processing of raw materials exported through the port. General engineering industries are connected with public utilities and with the sale, service, repair, and assembly of motor vehicles and other machinery; light manufacturers process food, drinks, and tobacco. Numerous factories are located on the city’s periphery.

Colombo has most of the amenities that a modern city has. Compared to other parts of the country, Colombo has the highest degree of infrastructure. Electricity, water and transport to street lamps, phone booths, etc. have a considerably good standard. The majority of the major shopping malls in Sri Lanka are in the city, of which all are wi-fi enabled. Apart from that, many luxurious hotels, clubs and restaurants are in the city. In recent times there has been an outpour of high rise condominiums, mainly due to the very high land prices.

Colombo Harbour is the largest and one of the busiest ports in Sri Lanka. The Port of Colombo handled 3.75 million twenty-foot equivalent units in 2008, 10.6% up on 2007 , bucking the global economic trend. Of those, 817,000 were local shipments with the rest transshipments. With a capacity of 5.7 million TEUs and a dredged depth of over 15 m , the Colombo Harbour is one of the busiest ports in the world, and ranks among the top 25 ports .

Colombo has an extensive public transport system based on buses operated both by private operators and the government owned Sri Lanka Transport Board . The three primary bus terminals – Bastian Mawatha, Central, and the Gunasinghapura Bus Terminals – are in Pettah. Bastian Mawatha handles long distance services whereas Gunasinghapura and Central handle local services. Train transport in the city is limited since most trains are meant for transport to and from the city rather than within it and are often overcrowded. Other means of transport includes auto rickshaws and taxicabs. Three wheelers are entirely operated by individuals and hardly regulated whilst cab services are run by private companies and are metered. Post-war development in the Colombo area also involves the construction of numerous expressway grade arterial road routes. The first of these constructed is the Southern Expressway, which goes from Kottawa, a southern suburb of Colombo, to Matara City in the south of the country. Expressways under construction in the Colombo metropolitan area include the Colombo–Katunayake Expressway which was opened in October 2013 and the Colombo orbital bypass Outer Circular Highway which is due to be opened in 2014. The Colombo-Katunayake Expressway runs from Peliyagoda, a northern suburb of Colombo, to Colombo International Airport and it linked with one of the major commercial hubs and a major tourist destination of the country, the city of Negombo.An international ferry liner, the Scotia Prince, is conducting a ferry service to Tuticorin, India. Ferry services between the two countries have been revived after more than 20 years.