When the American Revolution ended in 1783, suddenly the newly formed United States needed to figure out how to govern successfully without reverting back to an absolute ruler. Monarchies were so 1774.

It might be one of the most important parts of the U.S. Constitution, but the Bill of Rights actually wasn't included in the first draft. Most of the framers were convinced that a limited government was enough to protect individual liberties and basic rights. However, as the states debated over whether or not to ratify the Constitution, it started to feel like a pretty good idea—just in case.

The Bill of Rights is significant because it guarantees personal freedoms and rights, and it also places clear limitations on governmental power. You can thank the first 10 amendments for, among other things, the right to free speech, the right to bear arms, and the right to say "no" if a British soldier comes knocking on your door and asks to stay awhile.

You can also thank the Bill of Rights for directly influencing many of the articles in the Universal Declaration of Human Rights—free speech is in that one, too.