The iron law of oligarchy is a theory that says that any group or organization that is run by a few people will eventually be controlled by a small group of those people. It's called the "iron" law because it is so strong and hard to break. This can happen in companies, governments, and other organizations. The people in power try to make sure that only they have control over the group and that it stays in their hands. This can cause problems for the members of the group who don't have power, because the powerful people make decisions that only help them and not the rest of the members.