>>1296757today is the day the British Empire lost to rednecks and businessmen.
Basically the 13 American colonies were sick of all the ridiculous laws and taxes England were imposing on them, so they revolted, sent a Declaration of Independence to the King (which declared them an independent nation), and he sent troops to the colonies.
The colonies got together and fought the troops, and in 1783 the colonies (now called the United States of America) won against the most powerful military on Earth.
We as Americans celebrate this by shooting off millions of dollars in fireworks (to represent the mortar shells being used in the war), shooting guns, eating BBQ outside, self-mutilation, getting drunk off of malt liquor and Budweiser, and other traditions that I can't think of at the moment.