What Counts as a Hit
In baseball, a hit occurs when a batter safely reaches base after hitting the ball into fair play. A no-hitter means the pitcher prevents this from happening for an entire game. Even if batters reach base through walks or errors by fielders, it does not count against the no-hitter.
How a Team Can Score Without Hits
Although a pitcher throws a no-hitter, the opposing team can still score runs. This happens through walks combined with stolen bases, sacrifice plays, or errors by the defense. For example, a batter can walk, steal second base, move to third on a sacrifice, and score on a wild pitch, all without a hit being recorded.
Official Requirements
For a no-hitter to be recognized in Major League Baseball, the pitcher must complete at least five innings in a regulation game. In shorter games or rain-shortened games, different rules may apply. The pitcher does not have to be the winning pitcher, though this is common.
Historical Significance
No-hitters are celebrated as remarkable achievements because they require exceptional pitching and often good defensive support. Since 1900, fewer than 300 no-hitters have been thrown in Major League Baseball history. Some famous pitchers like Nolan Ryan hold records for throwing multiple no-hitters during their careers.
Perfect Game vs. No-Hitter
A perfect game is rarer and more impressive than a no-hitter. In a perfect game, the pitcher allows no hits, no walks, and no errors, meaning no opposing batter reaches base at all. A no-hitter is less restrictive and allows walks and errors as long as no hits are given up. 
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