Map of Sydney, NSW 2000

Sydney is the capital city of the state of New South Wales and the most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about 80 km (50 mi) from the Pacific Ocean in the east to the Blue Mountains in the west, and about 80 km (50 mi) from the Ku-ring-gai Chase National Park and the Hawkesbury River in the north and north-west, to the Royal National Park and Macarthur in the south and south-west. Greater Sydney consists of 658 suburbs, spread across 33 local government areas. Residents of the city are colloquially known as "Sydneysiders". The estimated population in June 2023 was 5,450,496, which is about 66% of the state's population. The city's nicknames include the Emerald City and the Harbour City.

Aboriginal Australians have inhabited the Greater Sydney region for at least 30,000 years, and their engravings and cultural sites are common. The traditional custodians of the land on which modern Sydney stands are the clans of the Darug, Dharawal and Eora peoples. During his first Pacific voyage in 1770, James Cook charted the eastern coast of Australia, making landfall at Botany Bay. In 1788, the First Fleet of convicts, led by Arthur Phillip, founded Sydney as a British penal colony, the first European settlement in Australia. After World War II, Sydney experienced mass migration and by 2021 over 40 per cent of the population was born overseas. Foreign countries of birth with the greatest representation are mainland China, India, the United Kingdom, Vietnam and the Philippines.

Despite being one of the most expensive cities in the world, Sydney frequently ranks in the top ten most liveable cities.