No Hitter vs. Perfect Game: Understanding the Difference in Baseball

Question
Excuse my English ignorance but I've really gotten into baseball recently and have a question...

What is the difference between a no hitter and a perfect game?  Thanks.

Answer
Antony,

A perfect game is when no batter reaches first base during the entire game.

A no hitter is when no batter has a safe hit during an entire game, but may reach base by a walk or by a fielder's error.

Perfect games are extremely rare - there have only been about 15 in the entire 140 year history of baseball.  No hitters are also rare, but they tend to happen 2-3 times per year on average.

Hope this helps!

Brian