- "3B" redirects here. It may also refer to a triple.
The third baseman (abbreviated 3B and position 5 when scoring) is the defensive player in the infield who plays closest to third base. The third baseman is an important defensive player, though the position has usually been considered to be slightly less challenging than shortstop or second base because the third baseman rarely needs to act as the pivot man on double plays.
Like the other infielders, the third baseman needs to be agile and able to start and stop quickly. The third baseman needs to have the quickest reflexes of any infielder because he usually plays closer to the batter than the second baseman or shortstop and balls hit toward third base (especially by right-handed batters) are often harder hit than those going toward the middle of the field. The large number of balls hit hard toward third base has given the position the nickname the hot corner. At the same time, the third baseman has an important job fielding balls bunted along the third base line, and the third baseman often must field a bunt with his bare hand and make an off-balance throw to first base to record an out. The need to make many long, accurate throws means that third basemen need to be excellent throwers. Third base has historically had the lowest fielding percentage of any position.
|Outfielders:||Left field | Center field | Right field|
|Infielders:||3rd base | Shortstop | 2nd base | 1st base|
- "Here are the best 3B in history, team by team", mlb.com, April 13, 2020. 
- Thomas Boswell: "The Importance of Being Third", in Why Time Begins on Opening Day, Penguin Books, New York, NY, 1984, pp.167-175.
- Mike Petriello: "Rolen could open HOF door to more third basemen. And soon", mlb.com, January 11, 2023.