New Territories, abbreviated to NT or N.T., is a region in Hong Kong excluding Hong Kong Island, Kowloon and Stonecutters Island. Historically, it is the region described in The Convention for the Extension of Hong Kong Territory. According to that the territories comprise the mainland area north of the Boundary Street of Kowloon Peninsula and south of the Sham Chun River which is the border between Hong Kong and Mainland China, as well as over 200 outlying Islands including Lantau Island, Lamma Island, Cheung Chau, and Peng Chau in the territory of Hong Kong.
Later, after the establishment of New Kowloon, the extension of urban Kowloon between the Boundary Street and the Kowloon Ranges spanned from Lai Chi Kok to Lei Yue Mun, the New Kowloon was gradually urbanised and absorbed into Kowloon and finally excluded from New Territories. Hence, the New Territories now is only the mainland north of the Kowloon Ranges and south of the Sham Chun River, as well as the Outlying Islands. It comprises an area of 952km² (368 sq mi). 
The New Territories were leased from Qing China to the United Kingdom in 1898 for 99 years in the Second Convention of Peking (The Convention for the Extension of Hong Kong Territory). Upon the expiration of the lease, it was transferred to People's Republic of China in 1997, together with the Qing ceded territories of Hong Kong Island and Kowloon Peninsula.
In 2006, New Territories had a population of 3,573,635 and its population density was 3,748 per km².
In January 1898, Germany was given a lease of Jiaozhouwan (Kiaochow) following the murder of two German missionaries by bandits in Shandong (Shantung) province. Seeking to expand its own influence in northeastern China, Russia demanded Port Arthur (Lüshunkou) in the nearby Liaodong (Liaotung) peninsula in March 1898. One month later, France was granted a lease for Guangzhouwan (Kwang-Chou-Wan) in Guangdong (Kwangtung), close to its existing colonies in Southeast Asia.
Alarmed by European encroachment in China, Britain also feared for the security of Hong Kong. Using the most favoured nation clause that it had negotiated with Peking, the United Kingdom demanded the extension of Kowloon to counter the influence of France in southern China in June 1898. In July, it secured Weihaiwei in Shandong in the north as a base for operations against the Germans in Qingdao (Tsingtao) and the Russians in Port Arthur. Chinese officials stayed in the wall cities of Kowloon City and Weihaiwei.
The extension of Kowloon was called the New Territories. The additional land was estimated to be 365 square miles (945 km2) or 12 times the size of the existing Colonial Hong Kong at the time.
The new Hong Kong Governor Henry Blake arrived in November 1898. A takeover date was chosen as 17 April 1899 and Tai Po was chosen as the administrative centre. However the transfer was not smooth and peaceful. Before the handover in early April, Captain Superintendent of Police, Francis Henry May and some policemen erected a flagstaff and temporary headquarters at Tai Po and posted the Governor's proclamation of the takeover date.
Lord Lugard was Governor from 1907 to 1912, and he proposed the return of Weihaiwei to the Chinese government, in return for the ceding of the leased New Territories in perpetuity. The proposal was not received favourably, although if it had been acted on, Hong Kong might have remained forever in British hands.
The New Territories comprise the following districts:
New Kowloon covers the entirety of the Wong Tai Sin and Kwun Tong districts, as well as the mainland portion of the Sham Shui Po District (i.e. excluding the Stonecutters Island) and the northern portion of the Kowloon City District (portion to the north of the Boundary Street/Prince Edward Road West, as well as reclaimed land including the Kai Tak Airport).