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Walk

If the count has three balls when a pitch comes in, and the pitch is called a ball, the result is a walk. Otherwise known as a base on balls, a walk simply means that the batter now automatically takes first base. You can also get a walk without a pitch if there are three balls in the count, and the pitcher commits a pitch timer violation, resulting in a fourth ball.

The ball does not go dead on a walk, and once the batter reaches first, they become a runner, and are in play for the defense. The vast majority of the time, a walked batter will simply head to first, and swap their "being a hitter" gear for their "being a baserunner" gear. But very occasionally, a batter will take a walk to first, notice that the defense isn’t paying attention, and then take off for second immediately¹. Unless time is called somewhere in there, this is a legal play.