There are two methods for formally amending the US Constitution outlined in Article V: proposal of an amendment by Congress or a national convention, and ratification by state legislatures or conventions. The Constitution has been formally amended 27 times, with the first ten amendments known as the Bill of Rights guaranteeing basic freedoms. While the text of the Constitution has only been formally amended a few times, it has also been informally amended over time through legislation, executive actions like treaties, and Supreme Court rulings interpreting the Constitution.