A precedent is an earlier example or decision that guides how similar situations should be handled in the future. When something becomes a precedent, it sets a pattern that others are expected to follow.

The word matters most in law. When judges make legal decisions, they often look at precedents: how similar cases were decided before. If a court ruled five years ago that students have the right to start after-school clubs, that decision becomes a precedent for similar cases. Future judges will study that ruling when students in other schools face the same issue.

But precedents aren't just for courtrooms. In your family, when your parents let your older sister stay up until 9:30 on school nights after she turned eleven, they set a precedent. Now you can reasonably expect the same privilege when you reach that age. In a classroom, if a teacher allows one student to turn in a project late because they were sick, that decision might set a precedent for how the teacher handles late work in the future.

The phrase “setting a precedent” means being the first to do something in a way that others might copy. People sometimes refuse to do something specifically because they don't want to set a precedent. They know that if they make an exception once, everyone will expect the same treatment going forward.