Modern knucklebones consist of six points, or knobs, projecting from a common base and are usually made of metal or plastic. However, different variants of the game from various cultures use other objects, including stones, seashells, seeds, and cubes. The name 'knucklebones' is derived from the Ancient Greek version of the game, which uses the astragalus (a bone in the ankle, or hock) of a sheep. It is ancient in origin and is found in various cultures worldwide. Knucklebones, also known as scatter jacks, snobs, astragaloi ( singular: astragalus), tali, dibs, fivestones, jacks, or jackstones, among many other names, is a game of dexterity played with a number of small objects that are thrown up, caught, and manipulated in various manners. A collection of jacks within the permanent collection of The Children's Museum of Indianapolis Pieter Bruegel the Elder – Children's Games (detail) – Knucklebones

For the anti-personnel device sometimes called a 'jackrock' in the U.S., see caltrop.

Jacks rules