A baseball glove or mitt is a large leather glove that baseball players on the defending team are allowed to wear to assist them in catching and fielding balls hit by the batter.

Some say the first player to use a baseball glove was Doug Allison, a catcher for the Cincinnati Red Stockings, in 1870, due to an injured left hand. While it was not accepted by all players at first, and in fact looked down upon by good defenders, it slowly caught on as more and more players began using different forms of gloves. Many early baseball gloves were simple leather gloves with the fingertips cut off, supposedly to allow for the same control of a bare hand, but with extra padding. The adoption of the baseball glove by baseball star Albert Spalding when he began playing first base influenced more infielders to begin using gloves. By the mid 1890s, it was the norm for players to wear gloves in the field.

Since their beginnings, baseball gloves have grown. While catching in baseball had always been two handed, eventually, gloves grew to a size that made it easier to catch the ball in the webbing of the glove, and use the off-hand to keep it from falling out.

Now, gloves have taken on many shapes and sizes:

• Catcher's mitts have extra padding and a shape that helps them to catch 90+ mile per hour fastballs, and provide a good target for pitchers to throw at. If required to catch a knuckleball, a catcher will typically use an even larger mitt.
• Pitcher's gloves usually have a closed webbing to allow them to get a grip on the ball without tipping their pitches
• First basemen's mitts are generally very long and wide, to help them with scooping badly thrown balls from infielders.
• Outfield gloves are usually quite long, to help with both catching fly balls on the run or on a dive and so they do not have to bend down as far to field a ground ball, so they can return it to the infield.
• Infield gloves other than the first basemens' tend to be smaller, to allow the players to easily fish the ball out with their bare hand to make a quick throw to first base.