Strike-out

In baseball or softball, a strikeout (or strike-out) occurs when a batter accumulates three strikes during a time at bat. It usually means the batter is out. A strikeout is a statistic recorded for both pitchers and batters, and is denoted by K.

Although a strikeout suggests that the pitcher dominated the batter, the free-swinging style that generates home runs also leaves batters susceptible to striking out. Some of the greatest home run hitters of all time — such as Alex Rodriguez, Gorman Thomas, Reggie Jackson, and Sammy Sosa — were notorious for striking out.

A pitched ball is ruled a ball by the umpire if the batter did not swing at it and, in that umpire's judgment, it does not pass through the strike zone. Any pitch at which the batter swings or, that in that umpire's judgment passes through the strike zone, is ruled a strike. Each ball and strike affects the count, which is incremented for each pitched ball with the exception of a foul ball on any count with two strikes. That is, a third strike may only occur by the batter swinging and missing at a pitched ball, or the pitched ball being ruled a strike by the umpire with no swing by the batter. A pitched ball that is struck by the batter with the bat on any count, and is not a foul ball or foul tip, is in play. A batter may also strike out by bunting, even if the ball is hit into foul territory.

A pitcher receives credit for (and a batter is charged with) a strikeout on any third strike, but a batter is out only if one of the following is true:

Thus, it is possible for a batter to strike out, but still become a runner and reach base safely if the catcher is unable to catch the third strike cleanly, and he then does not either tag out the batter or force him out at first base. In Japan, this is called furinige (振り逃げ^?), or "swing and escape". In Major League Baseball, it is known as an uncaught third strike. When this happens, a strikeout is recorded for both the pitcher and the batter, but no out is recorded. Because of this, a pitcher may occasionally be able to record more than three strikeouts in one half-inning.

...
Wikipedia