The 13 colonies were now part of Britain. The colonists were British citizens no matter where they lived.
That meant they had to follow British laws, or rules. A king ruled the British people. Before 1763, Britain did not worry much about life in the colonies. But after 1763, Britain needed money. So it passed laws to raise money from the colonists.
Many colonists thought that the British laws were unfair. They wanted to make their own laws. But they needed independence from Britain. Independence is the freedom of people to choose their own government. So the leaders of the colonies met. They wrote and signed the Declaration of Independence. It said that the colonies were now a new country.