The United States Declaration of Independence is a historic document adopted on July 4, 1776, by the thirteen American colonies. It announced their separation from British rule and outlined the principles of individual rights and government by consent. The Declaration was primarily authored by Thomas Jefferson and emphasized the belief that all men are created equal and have unalienable rights, including life, liberty, and the pursuit of happiness. The Declaration served as a formal statement of the colonies' grievances against King George III and the British government. It marked the beginning of the American Revolution and laid the foundation for the establishment of the United States of America. The document is celebrated annually on Independence Day.