Some of the most memorable baseball games are those in which one team doesn’t get a hit for all nine innings. They are called no-hitters.

Francisco Liriano of the Minnesota Twins and Justin Verlander of the Detroit Tigers recently threw no-hitters. Verlander almost threw a perfect game. That’s when a pitcher faces 27 batters in nine innings and gets them all out. No hits, no walks, no errors. Verlander gave up only one walk.

Perfect games are super exciting because they do not happen very often. There have been only 20 perfect games during the long history of Major League Baseball. Let’s look at some famous perfect (and almost perfect) games.

There has been only one no-hitter pitched in the World Series — and it wasn’t just a no-hitter, it was a perfect game. Don Larsen pitched it for the New York Yankees during the 1956 World Series against the Brooklyn Dodgers (who later moved to Los Angeles). The strange thing about Larsen’s perfect game was that Larsen was not a great pitcher. His career record was just 81 wins and 91 losses. But on October 8, 1956, Larsen was perfect.

Sandy Koufax was a great pitcher for the Los Angeles Dodgers. He was probably the best pitcher in baseball from 1961 to 1966, dominating hitters with his blazing fastball and knee-buckling curve. On September 9, 1965, Koufax was perfect, setting down 27 straight Chicago Cubs, 14 of them by strikeouts. Koufax had to be perfect: The Cubs’ pitcher, Bob Hendley, threw a one-hitter. The Dodgers beat the Cubs, 1-0.

Harvey Haddix, a left-handed pitcher for the Pittsburgh Pirates, pitched 12 perfect innings — that’s 36 straight outs — in a 1959 game against the hard-hitting Milwaukee Braves (who later moved to Atlanta). But Haddix still didn’t win the game. That’s because the Braves’ pitcher, Lew Burdette, did not give up a run for 12 innings, either. Haddix finally lost his perfect game on an error. He then gave up a walk and a hit, and he lost the game in the 13th inning.

Last season, Armando Galarraga almost became the 21st pitcher to throw a perfect game. Pitching for the Detroit Tigers, Galarraga had sat down the first 26 Cleveland Indians batters. Then the 27th batter appeared to have grounded out, but the umpire said he had beaten the throw to first base. So the batter was safe, and Galarraga’s chance for a perfect game was gone.

Replays showed (and the umpire later acknowledged) that the call was wrong. The 27th batter should have been called out. Galarraga, who now pitches for the Arizona Diamondbacks, showed he was a good sport as well as a good pitcher. He didn’t blame the umpire for the call and got the 28th batter out.

His behavior was just perfect.

Fred Bowen is the author of 16 books for kids, including a picture book, “No Easy Way: The Story of Ted Williams and the Last .400 Season.”