Triple
A hit that gets the batter to third. The rarest hit in the modern game.
What it actually is. A hit that reaches third base, which needs the ball placed where nobody can cut it off and a runner fast enough to be there when it is retrieved.
What a scout reads off it. The triple is the only hit that is more about the runner than the bat, and it is the one number in the box score that tells you a park's shape. Deep gaps and odd corners make triples; symmetrical fences kill them.
Where the lines are. Ten triples is a lot in the modern game, twenty is a genuine outlier. Sam Crawford's 309 career triples were compiled in the deadball era when outfields ran forever and are not going to be caught.
Batter's Eye: look up anything in baseball