When something happens to someone, it occurs by chance or circumstance rather than because they planned it or caused it. If you happen to find a dollar on the sidewalk, you weren't looking for it, but there it was. If your teacher happens to be an expert on volcanoes, that's just a fortunate coincidence when your class studies geology.

The phrase often signals something unexpected or unplanned. “I was walking to school and happened to see a fox” means you weren't fox-hunting, you were just lucky enough to spot one. “My mom happens to know your mom from college” explains a surprising connection.

Sometimes people use happens to when something unfortunate occurs: “If anything happens to my science project before the fair, I'll have to start over.” Here it means something bad might occur, though you hope it won't.

The phrase can also emphasize that something is simply true, even if it surprises others: “I happen to like Brussels sprouts” defends your taste when others disagree. You're saying this is just how things are, whether people expect it or not.