July 4 is a big deal here in the United States. It's our excuse to repeatedly blow stuff up. These days the USA and the UK are best friends.

Some stuff from Google:

On July 4, 1776, the Second Continental Congress unanimously adopted the Declaration of Independence, announcing the colonies' separation from Great Britain.

Before 1776, the United States of America was not a country. The individual states were colonies of the British Empire. They were called British Colonies. This means that the King and Parliament of Great Britain ruled the Colonies.