Two strokes under par on a hole — the bird theme escalating from birdie. In practice eagles almost always happen one of two ways: holing out in 3 on a par-5 (two big shots, then make the putt), or holing an approach shot on a par-4. They're rare enough that most amateurs remember every one they've ever made. Long hitters chase them on par-5s, which is why reachable par-5s are where tournaments swing.