Situational Hitting
Hitting to the spot the game needs.
How it actually works. With a runner on second and nobody out, a ground ball to the right side moves him to third and the run scores on almost anything after that. With a runner on third and fewer than two out, a fly ball to the outfield is worth more than a hard ground ball. With two outs, none of it applies and the hitter's job is simply to get on base.
Why it is done, and when it is wrong. The idea people get wrong is that this means giving yourself up. Mostly it does not. It means adjusting the target rather than the effort: looking for a pitch you can drive to the opposite field instead of one you can pull, or accepting a fly ball as a good outcome instead of trying to lift a ball you should be hitting on a line. The best situational hitters are not sacrificing, they are choosing among good outcomes.
What people get wrong about it. The productive out is overrated as a category, because outs are the scarce resource and a rally has a way of continuing if you simply do not make them. It is worth doing when the run is decisive and worth ignoring in the third inning of a game you are trying to blow open.
At Little League and travel ball. Ground balls to the right side and fly balls with a runner on third are things youth hitters can actually be taught to execute, and they win close games at those levels because youth defenses do not turn the plays that punish them.
Batter's Eye: look up anything in baseball