A regulation diamond has the following dimensions:
Batting Box: These are two squares on each side of home plate from which the player must stand to hit the ball. The pitcher may not throw the ball until the player is ready in the batting box.
Infield: The area generally covered in sand or dirt rather than grass, or an area extending just behind first, second and third bases (collectively, the bases).
Outfield: The area behind the bases that is generally grass is called the outfield.
Pitching Rubber: A rubber strip in the middle of the pitching mound from which the pitcher releases the ball. One foot must be on the rubber when the ball is released or a balk should be called by the umpire (runners advance one base each).
Note: In T-Ball the play is considered 'over' when the ball is returned to the pitcher or the catcher.