The informal amendment process is the phrase used when the meaning of the Constitution changes. When the actual wording of the Constitution is changed, it is known as the formal amendment process.
As the United States and society move forward, the meaning of the Constitution may need to be interpreted differently to reflect any changes. Though changing the written wording of the Constitution is a long and difficult process, the judicial system, political parties, the president or the legislature can define the wording or interpret it differently much easier. This is done through passing laws, legal campaigning, deciding court cases or exercising presidential powers.
To amend the constitution formally, the House of Representatives and the Senate must have a two-thirds vote. It is then ratified by the state legislatures.