The United States Declaration of Independence, formally The unanimous Declaration of the thirteen united States of America, is the pronouncement adopted by the Second Continental Congress meeting in Philadelphia, Pennsylvania, on July 4, 1776. Enacted during the American Revolution, the Declaration explains why the Thirteen Colonies at war with the Kingdom of Great Britain regarded themselves as thirteen independent sovereign states, no longer under British rule. With the Declaration, these new states took a collective first step in forming the United States of America. The declaration was signed by 56 of America's Founding Fathers, congressional representatives from New Hampshire, Massachusetts Bay, Rhode Island and Providence Plantations, Connecticut, New York, New Jersey, Pennsylvania, Maryland, Delaware, Virginia, North Carolina, South Carolina, and Georgia. The Declaration became one of the most circulated and widely reprinted documents in early American history.

The Lee Resolution for independence was passed by the Second Continental Congress on July 2 with no opposing votes. The Committee of Five had drafted the Declaration to be ready when Congress voted on independence. John Adams, a leader in pushing for independence, had persuaded the committee to select Thomas Jefferson to compose the original draft of the document, which Congress edited to produce the final version. The Declaration was a formal explanation of why Congress had voted to declare independence from Great Britain, more than a year after the outbreak of the American Revolutionary War. Adams wrote to his wife Abigail, "The Second Day of July 1776, will be the most memorable Epocha, in the History of America"; although Independence Day is actually celebrated on July 4, the date that the wording of the Declaration of Independence was approved.

After ratifying the text on July 4, Congress issued the Declaration of Independence in several forms. It was initially published as the printed Dunlap broadside that was widely distributed and read to the public. The source copy used for this printing has been lost and may have been a copy in Thomas Jefferson's hand. Jefferson's original draft is preserved at the Library of Congress, complete with changes made by John Adams and Benjamin Franklin, as well as Jefferson's notes of changes made by Congress. The best-known version of the Declaration is a signed copy that is displayed at the National Archives in Washington, D.C., and which is popularly regarded as the official document. This engrossed copy (finalized, calligraphic copy) was ordered by Congress on July 19 and signed primarily on August 2.The sources and interpretation of the Declaration have been the subject of much scholarly inquiry. The Declaration justified the independence of the United States by listing 27 colonial grievances against King George III and by asserting certain natural and legal rights, including a right of revolution. Its original purpose was to announce independence, and references to the text of the Declaration were few in the following years. Abraham Lincoln made it the centerpiece of his policies and his rhetoric, as in the Gettysburg Address of 1863. Since then, it has become a well-known statement on human rights, particularly its second sentence: "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."

The declaration was made to guarantee equal rights for every person, and if it had been intended for only a certain section of people, Congress would have left it as "rights of Englishmen". Stephen Lucas called it "one of the best-known sentences in the English language", with Joseph Ellis saying it contains "the most potent and consequential words in American history". The passage came to represent a moral standard to which the United States should strive. This view was notably promoted by Lincoln, who considered the Declaration to be the foundation of his political philosophy and argued that it is a statement of principles through which the United States Constitution should be interpreted.:126The Declaration of Independence inspired many similar documents in other countries, the first being the 1789 Declaration of United Belgian States issued during the Brabant Revolution in the Austrian Netherlands. It also served as the primary model for numerous declarations of independence in Europe and Latin America, as well as Africa (Liberia) and Oceania (New Zealand) during the first half of the 19th century.:113

The Continental Congress was a series of legislative bodies, with some executive function, for thirteen of Britain's colonies in North America, and the newly declared United States just before, during, and after the American Revolution. The term "Continental Congress" most specifically refers to the First and Second Congresses of 1774–1781 and may also refer to the Congress of the Confederation of 1781–1789, which operated as the first national government of the United States until being replaced under the Constitution of the United States. Thus, the term covers the three congressional bodies of the Thirteen Colonies and the new United States that met between 1774 and 1789.

The First Continental Congress was called in 1774 in response to growing tensions between the colonies culminating in the passage of the Intolerable Acts by the British Parliament. It met for about six weeks and sought to repair the fraying relationship between Britain and colonies while asserting the rights of colonists. The Second Continental Congress convened in 1775 in response to the breakout of hostilities in Massachusetts. Soon after meeting, this second Congress sent the Olive Branch Petition to King George III while also selecting George Washington as the head of the new Continental Army. After peace was not forthcoming, the same congress drafted and adopted the Declaration of Independence in July 1776, proclaiming that the former colonies were now independent sovereign states.

The Second Continental Congress served as the provisional government of the U.S. for most of the War of Independence. In March 1781, the nation's first Frame of Government, the Articles of Confederation, came into force, at which time the body became the Congress of the Confederation. This unicameral governing body would convene in eight sessions before disbanding in 1789, when the 1st United States Congress under the new Constitution of the United States took over the role as the nation's legislative branch of government.

Both the First and Second Continental Congresses convened in Philadelphia, though with the city's capture during the Revolutionary War, the Second Congress was forced to meet in other locations for a time. The Congress of Confederation was also established in Philadelphia and later moved to New York City when it briefly became the U.S. capital beginning in 1785.

Much of what is known today about the daily activities of these congresses come from the journals kept by the secretary for all three congresses, Charles Thomson. Printed contemporaneously, the Papers of the Continental Congress contain the official congressional papers, letters, treaties, reports and records. The delegates to the Continental and Confederation congresses had extensive experience in deliberative bodies, with "a cumulative total of nearly 500 years of experience in their Colonial assemblies, and fully a dozen of them had served as speakers of the houses of their legislatures."