The standard size board is 19x19 and is marked with a 19x19 lined grid. Some 19x19 sized boards had a 13x13 size board on the underside of the board. Smaller boards could have a 13x13 grid or a 9x9 grid (13x13 sized board, and 9x9 sized board respectively) that are often used to play shorter game and to help teach beginners how to play the game. In historical times, a 17x17 sized board was used. The shape that Go boards come in differs from country to country; Chinese boards tend to be square while Japanese boards are oblong, so that they appear to be a square when playing in a normal playing position.