Something self-evident is so obviously true that it doesn't need proof or explanation. When you look outside and see rain falling, it's self-evident that you'll get wet if you go out without an umbrella. The truth is right there in front of you.

The most famous use of this word comes from the Declaration of Independence, which states, “We hold these truths to be self-evident, that all men are created equal.” Thomas Jefferson and the other founders meant that this truth was so fundamental and clear that it shouldn't require elaborate arguments or proof.

But here's something interesting: what seems self-evident to one person might not be obvious to another. Two centuries ago, many people didn't find equality self-evident at all, which is why the Declaration had to argue for it. Sometimes calling something self-evident is actually a way of saying, “this should be obvious to any reasonable person,” even when it needs to be stated clearly.

In math, self-evident truths are called axioms: basic facts like “a whole is greater than any of its parts.” In everyday life, self-evident things are the obvious facts we build other ideas on, like knowing that practice improves skills or that broken promises damage friendships.