The Treaty was written at a time when British colonists were pressuring the Crown to establish a colony in New Zealand, and when some Māori leaders had petitioned the British for protection against French forces. It was drafted with the intention of establishing a British Governor of New Zealand, recognising Māori ownership of their lands, forests and other possessions, and giving Māori the rights of British subjects. It was intended to ensure that when the declaration of British sovereignty over New Zealand was made by Lieutenant Governor William Hobson in May 1840, the Māori people would not feel that their rights had been ignored. Once it had been written and translated, it was first signed by Northern Māori leaders at Waitangi, and subsequently copies of the Treaty were taken around New Zealand and over the following months many other chiefs signed. Around 530 to 540 Māori, at least 13 of them women, signed the Treaty of Waitangi, despite some Māori leaders cautioning against it. An immediate result of the Treaty was that Queen Victoria's government gained the sole right to purchase land. In total there are nine signed copies of the Treaty of Waitangi including the sheet signed on 6 February 1840 at Waitangi.
The text of the Treaty includes a preamble and three articles. It is bilingual, with the Māori text translated from the English. Article one of the English text cedes "all rights and powers of sovereignty" to the Crown. Article two establishes the continued ownership of the Māori over their lands, and establishes the exclusive right of pre-emption of the Crown. Article three gives Māori people full rights and protections as British subjects. However, the English text and the Māori text differ, particularly in relation to the meaning of having and ceding sovereignty. These discrepancies led to disagreements in the decades following the signing, eventually culminating in the New Zealand Wars.
During the second half of the 19th century, Māori generally lost control of the land they had owned, some through legitimate sale, but often due to unfair land deals or outright seizure in the aftermath of the New Zealand War. In the period following the New Zealand Wars, the New Zealand government mostly ignored the Treaty and a court case judgement in 1877 declared it to be "a simple nullity". Beginning in the 1950s, Māori increasingly sought to use the Treaty as a platform for claiming additional rights to sovereignty and to reclaim lost land, and governments in the 1960s and 1970s were responsive to these arguments, giving the Treaty an increasingly central role in the interpretation of land rights and relations between Māori people and the state. In 1975, the Waitangi Tribunal was established as a permanent commission of inquiry tasked with interpreting the Treaty, researching breaches of the Treaty by the British Crown or its agents, and to suggest means of redress. In most cases, recommendations of the Tribunal are not binding on the Crown, but settlements totalling almost $1 billion have been awarded to various Māori groups. Various legislation passed in the later part of the 20th century has made reference to the Treaty, but the Treaty has never been made part of New Zealand municipal law. Nonetheless, the Treaty is regarded as the founding document of New Zealand.
The first contact between the Māori and Europeans was in 1642, when Dutch explorer Abel Tasman arrived and was fought off, and again in 1769 when the English navigator Captain James Cook claimed New Zealand for Britain at the Mercury Islands. Nevertheless, the British government showed little interest in following up this claim for over half a century. The first mention of New Zealand in British statutes is in the Murders Abroad Act of 1817, which clarified that New Zealand was not a British colony (despite being claimed by Captain Cook) and "not within His Majesty's dominions." Between 1795 and 1830 a steady flow of sealing and then whaling ships visited New Zealand, mainly stopping at the Bay of Islands for food supplies and recreation. Many of the ships came from Sydney. Trade between Sydney and New Zealand increased as traders sought kauri timber and flax and missionaries purchased large areas of land in the Bay of Islands. This trade was seen as mutually advantageous, and Māori tribes competed for access to the services of Europeans that had chosen to live on the islands because they brought goods and knowledge that were essential to the local iwi (the Māori word for the social unit often called "tribe" or "people"). At the same time, Europeans living in New Zealand needed the protection that Māori chiefs could provide. As a result of trade, Māori society changed drastically up to the 1840s. They changed their society from one of subsistence farming and gathering to cultivating useful trade crops.