Jacks, also known as knucklebones, is a very old game, usually played with five small objects, or ten in the case of jacks. Originally the "knucklebones" (pieces) were those of a sheep, which were thrown up and caught.
Knucklebones consist of six points coming out of a base, and are usually made of metal or plastic. The winner is the first player to successfully complete a prescribed series of different throws. The simplest throw is tossing up one stone or bouncing a ball, and picking up one or more pieces from the table while the stone/ball is in the air. This continues until all five stones or knucklebones have been picked up. At first, one must pick up "onesies", next "twosies" , and so on, depending on the total number of pieces included. The playing area should be decided between the players since there is no official game rule regarding that.