The Stamp Act of 1765 (Duties in American Colonies Act 1765; 5 George III, c. 12) was an act of the Parliament of Great Britain which imposed a direct tax on the British colonies in America and required that many printed materials in the colonies be produced on stamped paper produced in London, carrying an embossed revenue stamp. Printed materials included legal documents, magazines, playing cards, newspapers, and many other types of paper used throughout the colonies, and it had to be paid in British currency, not in colonial paper money.The purpose of the tax was to pay for British military troops stationed in the American colonies after the French and Indian War, but the colonists had never feared a French invasion to begin with, and they contended that they had already paid their share of the war expenses. They suggested that it was actually a matter of British patronage to surplus British officers and career soldiers who should be paid by London.

The Stamp Act was very unpopular among colonists. A majority considered it a violation of their rights as Englishmen to be taxed without their consentconsent that only the colonial legislatures could grant. Their slogan was "No taxation without representation". Colonial assemblies sent petitions and protests, and the Stamp Act Congress held in New York City was the first significant joint colonial response to any British measure when it petitioned Parliament and the King.

One member of the British Parliament argued that the American colonists were no different from the 90-percent of Great Britain who did not own property and thus could not vote, but who were nevertheless "virtually" represented by land-owning electors and representatives who had common interests with them. Daniel Dulany, a Maryland attorney and politician, refuted this in a widely read pamphlet by pointing out that the relations between the Americans and the English electors were "a knot too infirm to be relied on" for proper representation, "virtual" or otherwise. Local protest groups established Committees of Correspondence which created a loose coalition from New England to Maryland. Protests and demonstrations increased, often initiated by the Sons of Liberty and occasionally involving hanging of effigies. Very soon, all stamp tax distributors were intimidated into resigning their commissions, and the tax was never effectively collected.Opposition to the Stamp Act was not limited to the colonies. British merchants and manufacturers pressured Parliament because their exports to the colonies were threatened by boycotts. The Act was repealed on 18 March 1766 as a matter of expedience, but Parliament affirmed its power to legislate for the colonies "in all cases whatsoever" by also passing the Declaratory Act. A series of new taxes and regulations then ensuedlikewise opposed by the Americans. The episode played a major role in defining the 27 colonial grievances that were clearly stated within the text of the Indictment of George III section of the United States Declaration of Independence, enabling the organized colonial resistance which led to the American Revolution in 1775.

The Parliament of Great Britain was formed in May 1707 following the ratification of the Acts of Union by both the Parliament of England and the Parliament of Scotland. The Acts ratified the treaty of Union which created a new unified Kingdom of Great Britain and created the parliament of Great Britain located in the former home of the English parliament in the Palace of Westminster, near the City of London. This lasted nearly a century, until the Acts of Union 1800 merged the separate British and Irish Parliaments into a single Parliament of the United Kingdom with effect from 1 January 1801.