New Delhi ⁱ/ˈnjuː dɛli/ is the capital city of India. As the national capital, New Delhi is the seat of executive, legislative, and judiciary branches of the Government of India. It also serves as the centre of the Government of the National Capital Territory of Delhi. New Delhi is situated within the metropolis of Delhi and is one of the nine districts of Delhi Union Territory.

The definition of New Delhi is unclear and the differentiation between Delhi and New Delhi is blurry. Even administratively, the demarcation between Delhi and New Delhi is not clear. Government of India and Government of Delhi have not clearly defined the area and boundaries of New Delhi. The boundaries of areas of New Delhi Municipal Council (NDMC) and New Delhi district of Delhi do not completely overlap. In 1920s, when British constructed New Delhi, there were only two Delhis' – the old walled city called Old Delhi and the new city designed by Edwin Lutyens to serve as capital of British India, which was called 'New Delhi'. The rest of Delhi was rural. But after independence as more and more areas around New Delhi urbanized they also became a part of New Delhi as they were also a part of Delhi which was 'new'. Now, almost all of National Capital Territory of Delhi, with exceptions of the old city called Old Delhi, Civil Lines area, Trans-Yamuna region, some rural areas and some underdeveloped parts of Delhi (e.g. Ashok Vihar, Timarpur, Nangloi, Sultanpuri, Mangolpuri, Badarpur etc.), is designated as 'New Delhi' in postal addresses. Especially, almost all the places in South, South-west, Central and West districts of Delhi are designated as New Delhi. Most of the time, the terms Delhi and New Delhi are used interchangeably.

Delhi (/ˈdɛli/; locally pronounced Dillee or Dehli), officially the National Capital Territory of Delhi (NCT), is the largest metropolis by area and the second-largest metropolis by population in India. It is the eighth largest metropolis in the world by population with 16.7 million inhabitants in the Territory at the 2011 Census. The region has been given special status of National Capital Region under The Constitution (69th Amendment) Act, 1991. There are nearly 22.2 million residents in the greater National Capital Region urban area (which also includes the cities Noida, Greater Noida, Ghaziabad, Gurgaon,Sonepat and Faridabad along with other smaller nearby towns).

Delhi is known to have been continuously inhabited since at least the 6th century BCE, though human habitation is believed to have existed since the second millennium BCE. Delhi is also widely believed to have been the site of Indraprastha, the legendary capital of the Pandavas during the times of the Mahabharata. Delhi re-emerged as a major political, cultural and commercial city along the trade routes between northwest India and the Gangetic plain after the rise of the Delhi sultanates. It is the site of many ancient and medieval monuments, archaeological sites and remains.