Independence Day or Fourth of July is the annual celebration of the United States' "birthday," the date of the passage of the Declaration of Independence by the Continental Congress on July 4, 1776. The first celebrations included bell ringing, bonfires, processions, and speeches. In some towns, these celebrations also had a mock funeral for the king, symbolizing the end of America's rule by the British monarchy. It was not until 1941, however, that Congress officially established the Fourth of July as a legal holiday. The date could easily have been July 2, the day on which the Continental Congress approved a resolution for independence, or August 2, the day on which the members of Congress actually signed the document. But it was on July 4 that the final text of the Declaration, which had been drafted by Thomas Jefferson, was ratified. By 1788, the Fourth of July also commemorated the U.S. Constitution as well, which had recently been approved by ten states.

Feasting has always been part of Fourth of July celebrations. In the beginning there were banquets, but this has evolved into outdoor barbecues and picnics. Barbecue was originally a word for a wooden framework for sleeping or for drying or storing meat or fish. The word derives from Arawak or Haitian or Taina barbacoa and became Spanish barbacoa, "wooden frame on posts" or "framework for meat over fire." Barbeque is the variant spelling. In English, the word's first meanings were the framework and the animal roasted on it; the usage of "social entertainment" is not recorded until 1733. Picnic is from French pique-nique, but that word's origin is unknown. Picnics started out as social occasions (the word first recorded in English in 1748) to which each participant brought comestibles.

The bald eagle (also called the American or white-headed eagle, Haliaeetus leucocephalus) is the national bird of the United States and one of the largest birds in the world. "Bald" in this instance means "white," not "hairless." Eagle comes from the Latin word aquila, "black eagle," from aquilus, "dark-colored," which it is until it gets the white head plumage as an adult. The eagle has been a symbol of freedom and liberty and power since ancient times. Some people, like Benjamin Franklin, did not agree that the eagle was an appropriate symbol. Franklin thought the turkey was a better choice for the national bird.

The term for a combustible or explosive or pyrotechnic ("pertaining to fire art") projectile was "rocket" until fireworks was used in 1777 to describe these in connection with the first Fourth of July celebration. "Rockets" are still the most popular form of firework. Rockets are lifted by recoil from the jet of fire created by the burning ingredients — and they are designed for maximum combustion and maximum thrust. Fireworks originated in ancient China. The word firecracker refers to those that make loud sounds and sparklers are those that send off a shower of sparks. The very first Fourth of July celebrations in 1777 included fireworks as a part of the festivities.

A flag as a piece of cloth used as a standard, signal, or symbol in English dates to the late 15th century. The word may be an onomatopoeic representation for such a cloth flapping in the wind, but the origin remains obscured. As far as the American flag goes, there are many theories about its origin, with the story of Betsy Ross being the most famous.

The first Fourth of July parade took place on the Potomac River in Washington, D.C. when President John Quincy Adams led a boat procession up the river. Parade comes from a French word meaning "a showing" or "action of stopping a horse," originating from Latin parare, "to prepare."