A ball-jointed doll is any doll

Doll

A doll is a model of a human being, often used as a toy for children. Dolls have traditionally been used in magic and religious rituals throughout the world, and traditional dolls made of materials like clay and wood are found in the Americas, Asia, Africa and Europe. The earliest documented dolls...

 that is articulated with ball and socket joint

Ball and socket joint

A ball and socket joint is a joint in which the distal bone is capable of motion around an indefinite number of axes, which have one common center...

s. In contemporary usage when referring to modern dolls, and particularly when using the acronyms BJD or ABJD, it usually refers to modern Asian ball-jointed dolls. These are cast

Resin casting

Resin casting is a method of plastic casting where a mold is filled with a liquid synthetic resin, which then hardens. It is primarily used for small scale production like industrial prototypes and dentistry...

 in polyurethane

Polyurethane

A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

 synthetic resin

Synthetic resin

Synthetic resins are materials with a property of interest that is similar to natural plant resins: they are viscous liquids that are capable of hardening permanently. Otherwise, chemically they are very different from the various resinous compounds secreted by plants .The synthetics are of several...

, a hard, dense plastic, and the parts strung together with a thick elastic. They are predominantly produced in Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, South Korea

South Korea

The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...

 and China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. The BJD style has been described as both realistic and influenced by anime

Anime

is the Japanese abbreviated pronunciation of "animation". The definition sometimes changes depending on the context. In English-speaking countries, the term most commonly refers to Japanese animated cartoons....

.