A pitched ball that is judged to be 'against the batter'. Typically, this occurs when the batter swings and misses, fouls, or when the ball passes through the 'strike zone'.
A pitched ball that is judged to be 'against the pitcher'. This occurs when the ball passes through the 'strike zone' and and the batter does not swing.
A ball that does not stay within the confines of the foul lines (when the hit is wide). The hit is counted as a strike if the batter has less than three strikes.