Crocodile clip

A crocodile clip (or spring clip) is a temporary electrical connector, named for its resemblance to a crocodile's jaws. Functioning much like a spring-loaded clothespin, the clip's two tapered, serrated jaws are forced together by a spring to make them grip a metal object. One of the jaws usually has either a wire permanently attached or a 4 mm banana plug inserted into it, for connection to an electrical circuit. The clip may be partly covered by a plastic shroud or "boot" to prevent accidental short-circuits.

Smaller versions are used in electrical laboratory work. These have a slightly different shape and are called alligator clips.

Large versions of these clips, called automotive clips, made of bare copper, are fitted to car jumper cables, which are used to transfer energy from a charged lead-acid battery to a discharged one.

Other uses

Alligator clips are used in dental offices to attach a protective bib over the patient's clothing.
Crocodile and alligator clips are frequently used in school physics laboratories to quickly and cheaply assemble circuits. They are useful for connecting components to wires.
Alligator clips are used in fencing to connect to the lamé vests.
Alligator clips can be used as miniature clamps to hold parts together for gluing and wires together for soldering.
Helping Hands typically have two alligator clips.
Another type of crocodile clip is one which clips onto a tarp to allow a rope attachment to it. It serves the same purpose as a grommet.
As a roach clip for smoking cannabis.
Useful for airborne scenes in possible stop-motion or holding models of any sort in mid air.
crocodile clips can be used in Phreaking.
Useful as a heat sink while soldering heat sensitive transistors to a circuit board.

Kelvin clip

A Kelvin clip is a type of crocodile clip where the 2 jaws are insulated from each other. 2 wires connect to each clip. This enables 4 wire circuit measurement.