After a baseball player reaches base, a million things can happen to him — and the worst of them is getting put out. The following is a short list of the most common ways base runners suffer that fate. You should refer to it if you want to make sure why an out was made, or anticipate how one could be made — or avoided.
You’re on the same base with a teammate when the ball is alive (the second runner is out).
You pass a preceding runner on the base paths.
You miss a base and the defense notices it and gets the ball to the fielder closest to that base, which he must tag.
A fielder tags you with a ball that is alive while you’re off the base. (However, no one can tag you out if you overrun first base provided you return immediately to that bag without making an attempt toward second.)
Your teammate hits a ball that touches you in fair territory without it first touching or passing any fielder except the pitcher.
In the judgment of the umpire, you hinder a fielder from making a play.
A batted ball forces you to advance to another base, and the fielder possessing the ball tags that base before you reach it.