Sydney is the largest city in Australia and Oceania, and the state capital of New South Wales. Sydney has a metropolitan area population of approximately 4.5 million and an area of approximately 12,000 square kilometres (4,633 sq mi). Its inhabitants are called Sydneysiders, and Sydney is often called "the Harbour City". It is one of the most multicultural cities in the world, reflecting its role as a major destination for immigrants to Australia.

The site of the first British colony in Australia, Sydney was established in 1788 at Sydney Cove by Arthur Phillip, commodore of the First Fleet. The city is built on hills surrounding Sydney Harbour – an inlet of the Tasman Sea on Australia's south-east coast. It is home to the iconic Sydney Opera House, the Harbour Bridge and its beaches. The metropolitan area is surrounded by national parks, and contains many bays, rivers and inlets.

The city is home to many prominent parks, such as Hyde Park, Royal Botanical Gardens and national parks. This is a major factor, along with Sydney Harbour, that has led to the city’s reputation as one of the most beautiful in the world.

Sydney is considered an alpha+ world city, as listed by the Loughborough University group's 2008 inventory, is ranked 16th among global cities by Foreign Policy's 2008 Global Cities Index and is an international centre for commerce, arts, fashion, culture, entertainment, education and tourism. According to the Mercer cost of living survey, Sydney is Australia’s most expensive city, and the 66th most expensive in the world. Sydney also ranks among the top 10 most livable cities in the world according to Mercer Human Resource Consulting and The Economist.

Sydney has been ranked 14th within the top 50 global financial cities as surveyed by the Mastercard Worldwide Centers of Commerce Index (2007), and 1st within Australia. Sydney has hosted major international sporting events, including the 1938 British Empire Games, 2000 Summer Olympics, the final match of the 2003 Rugby World Cup, as well as the 2008 World Youth Day. The main airport serving Sydney is Sydney Airport.

The largest economic sectors in Sydney, as measured by the number of people employed, include property and business services, retail, manufacturing, and health and community services. Since the 1980s, jobs have moved from manufacturing to the services and information sectors. Sydney provides approximately 25 percent of the country's total GDP.

The Australian Securities Exchange and the Reserve Bank of Australia are located in Sydney, as are the headquarters of 90 banks and more than half of Australia's top companies, and the regional headquarters for around 500 multinational corporations. Of the ten largest corporations in Australia by revenue, four have headquarters in Sydney: Caltex Australia, the Commonwealth Bank, Westpac, and Woolworths. Of the 54 authorised deposit-taking banks in Australia, 44 are based in Sydney including nine of the 11 foreign subsidiary banks in Australia and all of the 29 local branches of foreign banks. Major authorised foreign banks in Sydney include Citigroup, UBS Australia, Mizuho Corporate Bank, HSBC Bank Australia and Deutsche Bank.

Shopping locations in the central business district include the Queen Victoria Building, the pedestrian mall on Pitt Street, and international luxury boutiques in the quieter, northern end of Castlereagh St. Oxford Street in Paddington and Crown Street, Woollahra are home to boutiques selling more niche products, and the main streets of Newtown and Enmore cater more towards students and alternative lifestyles.

Sydney received 7.8 million domestic visitors and 2.5 million international visitors in 2004. In 2007, the (then) Premier of New South Wales, Morris Iemma established Events New South Wales to "market Sydney and NSW as a leading global events destination". Fox Studios Australia has large film studios in the city.

As of 2004, the unemployment rate in Sydney was 4.9 percent. According to The Economist Intelligence Unit's Worldwide cost of living survey, Sydney is the sixteenth most expensive city in the world, while a UBS survey ranks Sydney as 15th in the world in terms of net earnings. As of September 2009, Sydney has the highest median house price of any Australian capital city at $569,000, and a median unit price of $400,000. Sydney also has the highest median rent prices of any Australian city at $450 a week.

The Sydney Region accounts for 12 percent (approximately $1 billion per annum) of the total agricultural production, by value, of NSW. Sydney provides 55% of NSW's flower production and 58% of its turf production, as well as 44% of state's nurseries. In 1994-1995 Sydney produced 44% of New South Wales' poultry meat and 48% of the state's eggs.