What you the most common and least used method used to add an amendment to the constitution?

The most common method to add an amendment to the U.S. Constitution is through a two-thirds majority vote in both the House of Representatives and the Senate, followed by ratification from three-fourths of the state legislatures. The least used method involves a constitutional convention called by two-thirds of state legislatures, where an amendment can be proposed and then sent to the states for ratification. This method has never been successfully used to amend the Constitution.