Sydney is the most populous city in Australia, with a metropolitan area population of approximately 4.28 million. Sydney is the state capital of New South Wales, and is the site of the first European colony in Australia, established in 1788 at Sydney Cove by Arthur Phillip, leader of the First Fleet from Britain. A resident of the city is referred to as a Sydneysider.

Sydney is located on Australia's south-east coast. The city is built around Port Jackson, which includes Sydney Harbour, leading to the city's nickname, "the Harbour City". Sydney is the largest corporate and financial centre in Australia and is also an important financial centre in the Asia Pacific. The Australian Stock 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. Sydney's leading economic sectors include property and business services, retail, manufacturing, tourism, media, and health and community services.

Sydney is a major international tourist destination notable for its beaches and twin landmarks: the Sydney Opera House and the Harbour Bridge. In 2004 Sydney had 7.8 million domestic visitors and 2.5 million international visitors. The metropolitan area is surrounded by national parks, and contains many bays, rivers and inlets. It has been recognised as a global city by the Loughborough University group's 1999 inventory. The city has played host to numerous international sporting events, including the 1938 British Empire Games, 2000 Summer Olympics and the 2003 Rugby World Cup. In September 2007, the city hosted the leaders of the 21 APEC economies for APEC Australia 2007, and in 2008 will host World Youth Day.

Sydney hosts many different festivals and some of Australia's largest social and cultural events. These include the Sydney Festival, Australia's largest arts festival which is a celebration involving both indoor and free outdoor performances throughout January; the Biennale of Sydney, established in 1973; the Big Day Out, a travelling rock music festival which originated in Sydney; the Gay and Lesbian Mardi Gras along Oxford Street; the Sydney Film Festival and many other smaller film festivals such as the short film Tropfest and Flickerfest. Australia's premier prize for portraiture, the Archibald Prize is organised by the Art Gallery of New South Wales. The Sydney Royal Easter Show is held every year at Sydney Olympic Park, the final of Australian Idol takes place on the steps of the Opera House, and Australian Fashion Week takes place in April/May. Also, Sydney's New Years Eve and Australia Day celebrations are the largest in Australia.

Sydney is now one of the most multicultural cities in the world which reflects its role as a major destination for immigrants to Australia. In the 2006 census, the most common self-described ancestries identified for Sydney residents were Australian, English, Irish, Scottish and Chinese. The Census also recorded that 1% of Sydney's population identified as being of indigenous origin and 31.7% were born overseas. According to the Mercer cost of living survey, Sydney is Australia's most expensive city, and the 21st most expensive in the world.

Sporting teams based in the city include:
Aussie Rules (AFL): Sydney Swans
Basketball (NBL): Sydney Kings · West Sydney Razorbacks
Cricket: New South Wales Blues
A-League Soccer: Sydney FC
Rugby League (NRL): Bulldogs · Cronulla-Sutherland Sharks · Manly-Warringah Sea Eagles · Parramatta Eels · Penrith Panthers · St George Illawarra Dragons · South Sydney Rabbitohs · Sydney Roosters · Wests Tigers
Rugby Union (Super 14): New South Wales Waratahs

Sydney has been voted the world's number one city by readers of the US magazine Conde Nast Traveler. It is the 11th time the harbour city has won the award since it began in 1988.