Sydney serves as the capital city of New South Wales and stands as the most populous urban center in Australia. Situated on the country’s east coast, the metropolis surrounds Sydney Harbour and extends approximately 80 kilometres from the Pacific Ocean to the Blue Mountains. It also stretches from Ku-ring-gai Chase National Park in the north to Royal National Park in the south. The broader metropolitan area, known as Greater Sydney, encompasses 658 suburbs distributed across 33 local government areas.

The region was inhabited by Aboriginal Australians for at least 30,000 years, with traditional custodians including the Darug, Dharawal, and Eora clans. European settlement began in 1788 when Captain Arthur Phillip established a British penal colony at Sydney Cove following his arrival at Botany Bay. The settlement was named after Home Secretary Thomas Townshend, 1st Viscount Sydney. Sydney was officially declared a city in 1842 and later became the first European settlement in Australia.

The city is characterized by its iconic landmarks, including the World Heritage-listed Sydney Opera House and the Sydney Harbour Bridge. It features over 1,000,000 hectares of nature reserves and parks, such as Royal National Park. The urban core is compact, surrounded by sprawling suburbs that form a vast metropolitan area. Notable districts include Darling Harbour, The Rocks, and the central business district, which is shaped roughly like a palm-up left hand.

Sydney attracts millions of tourists annually, ranking among the top fifteen most-visited cities worldwide. It has hosted major international events, including the 2000 Summer Olympics and the 2023 FIFA Women's World Cup Final. The city is recognized for its cosmopolitan culture, with significant populations from mainland China, India, the United Kingdom, Vietnam, and the Philippines. Its reputation as a liveable city is supported by strengths in education, finance, manufacturing, and tourism.

The estimated population was 5,450,496 as of 2023, with projections reaching 5,638,830 by June 2025. Sydney possesses an advanced market economy and is classified as an Alpha+ city by the Globalization and World Cities Research Network. Transportation infrastructure includes Kingsford Smith Airport, one of the world's oldest continually operating airports, and Central Station, which serves as the hub for suburban train, metro, and light rail networks.