Americans are celebrating the Fourth of July, which marks an event of massive historical significance for the country. If you're unsure of why Americans celebrate it, or where it comes from, here is everything you need to know.

What is it?

The Fourth of July is the most significant national holiday in the United States. It celebrates the Declaration of Independence, adopted on 4 July, 1776. The Thirteen Colonies of America declared themselves to be states and no longer part of the British Empire, though the revolutionary war continued for some time after.

What’s the story behind it?

The original United States of America was made up of a collection of East Coast states known as the Thirteen Colonies. These were: Delaware, Pennsylvania, New Jersey, Georgia, Connecticut, Massachusetts Bay, Maryland, South Carolina, New Hampshire, Virginia, New York, North Carolina, and Rhode Island and Providence Plantations.

These mainly agricultural colonies were run by the British - who had been present on the continent since 1587 - and exploited for their resources, in particular tobacco.

While the relationship between the settlers and British was once amicable, tensions began to escalate over British laws and taxes, such as the Sugar Act, driven by British financial needs. There was also a growing sense of nationalism in the country.

From 1765, some settlers began to demand "no taxation without representation", calling for their voices to be heard in the British parliament.

This tension sometimes erupted into fighting and acts of dissent, such as the Boston Tea Party in 1773. The event was a protest against the Tea Act, legislation which gave the British East India Company a monopoly on sales of tea in the Thirteen Colonies.

Further ill feeling was caused by the Coercive Acts – which became known as the "Intolerable Acts" to American Patriots – which were implemented in response to the Boston Tea Party. The laws took power away from semi-autonomous Massachusetts.

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Google celebrates US Independence Day with an interactive doodle google-doodlev1.jpg Google celebrates US Independence Day with an interactive doodle v2googledoodle.jpg On 11/11/12 Google doodle celebrates 125 years of LS Lowry Google celebrates US Independence Day with an interactive doodle google-doodle-star-trek.jpg September 8, 2012: One for the Trekkies, this Google Doodle is interactive and takes the viewer through a series of scenes that feature in the series, taking them to another planet and encountering strange creatures. 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This Doodle celebrates Moog's 78th birthday Google celebrates US Independence Day with an interactive doodle Untitled-1.jpg Google created a 'doodle' celebrating what would have been the 101st birthday of origami master Akira Yoshizawa on 14 March 2012. Google celebrates US Independence Day with an interactive doodle google-doodle-dickens.jpg Feb 7, 2012: Google created an homage to Charles Dickens on his 200th birthday. There are some clearly recognisable characters in this Doodle, which was created with the help of Dickens fans Google celebrates US Independence Day with an interactive doodle google.0d171053302.w400.jpg A screenshot of Google's Alexander Calder doodle All rights reserved Google celebrates US Independence Day with an interactive doodle Vasari.jpg This Google doodle in tribute to Giorgio Vasari's 500th birthday appeared on the search engine's home page in Italy on 30th July 2011. Google celebrates US Independence Day with an interactive doodle GeorgeGilbert.jpg English architect Sir George Gilbert Scott's 200th Birthday was celebrated with this Google doodle on 13th July 2011. Google celebrates US Independence Day with an interactive doodle google-doodle-les-paul.jpg June 9, 2011: This interactive guitar was inspired by Les Paul, arguably one of the most famous guitar developer, on what would have been his 96th birthday Google celebrates US Independence Day with an interactive doodle google-doodle-pac-man.jpg May 21, 2010: This Doodle was hugely popular and it's not hard to see why. Fans of the old Pac-Man game could play this interactive version around the Google logo, in celebration of its 30th birthday Google celebrates US Independence Day with an interactive doodle google-doodle-royal-wedding.jpg April 29, 2011: The Royal Wedding Doodle was 'challenging' as the buildings had to be in the shape of the logo. This, of course, was displayed on Google the same day that Prince William and Kate Middleton got married Google celebrates US Independence Day with an interactive doodle google-doodle-jules-verne.jpg Feb 8, 2011: Jules Vernes' 183rd birthday Doodle was interactive , where the lever could be moved to change the view in the porthole windows. 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In response to these factors, Continental Congresses – a meeting of delegates from the Thirteen Colonies – were convened. At the second meeting, in 1775, a war of independence against Britain was declared.

The next year, the Declaration of Independence was signed by 56 representatives of thirteen self-styled states (previously the Thirteen Colonies). The signatories included future president Thomas Jefferson and Benjamin Franklin.

The conflict continued until the 1783 Treaty of Paris, which ended the war in favour of an independent America.

How has it been celebrated through history?

Fireworks, speeches, parties, feasts and general celebrations have marked the day since the 18th century. In Bristol, Rhode Island, there was a salute of 13 gunshots in the morning and evening in 1777. The town has held the nation's longest running Independence Day celebration.

In 1778, George Washington, then a general in the revolutionary army, issued his troops with a double rum ration.

The first recorded music commemorating independence was the ‘Pslam of Joy’, written by Johann Friedrich Peter in Salem, North Carolina.

Many towns and cities across the US have their own annual celebrations.

How has the government marked it?

Congress made the day an unpaid national holiday for federal workers in 1870, and in 1938 it became a paid holiday across the country. Government officials also take part in celebratory functions and make speeches.

How do people celebrate it today?