A baseball park, baseball stadium, or ball park / ballpark is the field of play in the game of baseball and the spectator seating areas (if any) and any other features connected with it.

The flexible rules about baseball fields (aside from the rigid rules of sizes of basepaths and pitcher's mound) allow ballparks to have their own individual character and quirks. This is true at all levels of baseball, amateur and professional, in countless cities and towns where the game is played. This article focuses on Major League Baseball venues, which typically have the largest seating areas and receive the broadest media coverage.

General characteristics

The infield is a rigidly structured "diamond" (actually a square) containing the bases, home plate, and the pitcher's mound. Two white foul lines run perpendicular along two of the sides from the plate, forming the boundaries of what's in play and what's out of play.

Next to first and third base, are two coach's boxes, where the first and third base coaches guide the baserunners. Farther on the other side of the foul lines are the dugouts where the teams and coaches sit when they're not out on the field.

Beyond the infield, and between the foul lines, is a large grass outfield, generally twice the depth of the infield. The other side of the outfield is set by the outfield fences, which end the field of play. There are also fences in foul territory, although these are significantly lower in most places, especially around the infield.

In modern days, a ballpark is mostly surrounded by a multi-tiered seating structure, a grandstand. This often ends a short distance into fair territory, the area beyond the outfield fences being a more open area, perhaps with a view of the buildings beyond. This open area may contain shorter disconnected grandstands, bleacher seats, scoreboards, fountains, or open-air museums, just to name a few. In some Jewelbox and multi-purpose parks, the grandstand completely surrounds the field.

Starting with Yankee Stadium in 1923 (as an actual footrace track) and now present in all ballparks, there is a dirt (or in some parks, rubberized track surface) area roughly 10 feet wide which runs all about the perimeter of the field, called the "warning track". As the name indicates, this track is intended to warn fielders (especially outfielders) that they are approaching a boundary wall of the playing field.

The term "ballpark" is sometimes used ambiguously, as either the entire structure or just the playing field. A home run which occurs within the confines of the playing field is typically called an "inside-the-park" home run, as opposed to a home run over a fence and into the seats (if any). That might be referred to as a home run "out of the ballpark". That phrase is more often used to mean a home run which clears the stands and lands outside the building.