Intentional Walks and Pitching Around
Put the hitter on first on purpose.
How it actually works. It is signaled from the dugout and, in the professional game, no longer requires four thrown pitches. The classic use is first base open with a runner on second and a dangerous hitter up: the walk creates a force at every base, makes the double play available, and moves the at bat to somebody else.
Why it is done, and when it is wrong. The honest summary is that it is usually a bad idea and occasionally a very good one. Handing out a free baserunner is worse than almost any hitter's realistic outcome, because even a great hitter makes an out most of the time, and the walk turns a probability into a certainty. The situations where it works are narrow: first base open, a double play available, a large gap in quality between this hitter and the next, and late enough that the inning's runs are decisive. Outside that, it is a manager buying safety with a run.
What people get wrong about it. The unintentional intentional walk, meaning four pitches deliberately off the plate that the hitter might still chase, is usually the better version of the same idea. It gets you the walk if he takes and a bad swing if he does not.
At Little League and travel ball. At youth levels walking a hitter to get to the next one is almost always wrong, and it also teaches something you do not want to teach. Pitch to him.
Batter's Eye: look up anything in baseball