A type of chain, made of metal (usually steel or brass), formed by a series of hollow spherelets, connected by tiny barbels. The two blobs on the ends of a barbel are trapped inside two spheres, and the shaft of the barbel links them together.

Ball chain can also be called "bead chain". Is this a UK term?

Ball chain comes in many sizes, from guage 1 (spheres are less than 2 mm) up to guage 20 (spheres are up to 10 mm). There are also shape variations -- the spheres can be elongated, eliptical, faceted, etc. There is a factory that manufactures it in Mt. Vernon, NY. Some outfits sell "ball chain" which is plastic beads molded onto a string, but that is not nearly as cool as the real thing.

Ball chain has many uses: as inexpensive jewelry (a simple big-guage ball chain choker is very fetching, especially among industrial types), as a keychain, or as a lanyard for hanging your ID card or backstage pass around your neck. Ball chain and black leather look nice together -- e.g., large-guage ball chain straps on a black leather bra. Some researchers with the US Geological Survey have successfully used ball chain as a way to attach a radio collar to frogs and kangaroo rats to track them for study (http://www.npwrc.usgs.gov/resource/tools/telemtry/ranid.htm).

Ball chain is better than link chain in applications where tangling and twisting are to be avoided. Each ball in a length of ball chain is a tiny swivel, allowing the chain to twist freely without kinking.