The U.S. Constitutional Amendments are changes or additions to the original U.S. Constitution. There are currently 27 amendments, with the first ten known as the Bill of Rights, which were ratified in 1791. These amendments outline fundamental rights and freedoms, such as freedom of speech and the right to bear arms. Amendments can be proposed by a two-thirds majority in both houses of Congress or by a national convention called by two-thirds of state legislatures. To become law, an amendment must be ratified by three-fourths of the states, ensuring that changes reflect a broad consensus.