A chain is a series of connected links which are usually made of metal. A chain may contain two or more links.
Chains are generally made in one of two styles, as per their intended use:
· Those intended for lifting, such as when employed with a hoist; for pulling; or for safety, such as with a bicycle lock, have links that are torus shaped, which make the chain flexible in two dimensions (The fixed third dimension being a chain's length.)
· Those intended for carrying power in machines have links planned to interconnect with the teeth of the sprockets of the machine, and are flexible in only one dimension. They are identified as roller chains, though there are also non-roller chains such as block chain.
Two separate chains can be linked using a quick link which looks like a carabiner with a screw close rather than a latch.