We have two ways of being able to change and modify the constitution. It’s just had its 226th birthday on September 17th, and is still advancing and going to this very day. Without formal and informal amendments we wouldn’t have been able to add constitutions as times have changed and how years and technology have advanced.
From my perspective, formal amendments is probably one of the main ways we change the constitution. Basically annotating, as in revising and adding some things. But you cannot just write new amendments, rules and or laws, there’s quite a process before that can happen. There are about 4 different arrangements for this process. This new amendment needs to be brought up or pitched by Congress or