Final answer:
In 2010, Roy Halladay pitched two no-hitters for the Philadelphia Phillies, one in the regular season and one in the postseason, representing a rare accomplishment in Major League Baseball.
Step-by-step explanation:
In 2010, Roy Halladay of the Philadelphia Phillies threw two no-hitters, achieving this rare feat both in the regular season and in the postseason. A no-hitter in Major League Baseball is an impressive accomplishment where a pitcher, or a combination of pitchers, does not allow the opposing team to get any hits during the entire game.
The regular-season no-hitter occurred on May 29, 2010, against the Florida Marlins, and the postseason no-hitter, which is even more uncommon, happened on October 6, 2010, in the first game of the National League Division Series against the Cincinnati Reds. The fact that these events are statistically rare with an average occurrence of about three per season and that the time between no-hitters is described by an exponential distribution speaks to the significance of Halladay's achievements.