Sydney is the capital city of the Australian state of New South Wales and serves as the most populous city in Australia. Located on the nation's east coast, the metropolis surrounds Sydney Harbour and spans approximately 80 kilometres from the Pacific Ocean in the east to the Blue Mountains in the west.
The urban area extends roughly 80 kilometres from 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 is composed of 658 suburbs distributed across 33 local government areas.
As of June 2025, the city had an estimated population of 5,638,830, representing about 66% of the state's total population. Residents are colloquially referred to as "Sydneysiders," and the city is known by the nicknames the Emerald City and the Harbour City.