A crocodile clip is a simple mechanical device for creating a temporary electrical connector

Electrical connector

An electrical connector is an electro-mechanical device for joining electrical circuits as an interface using a mechanical assembly. The connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires or...

, and is named for its resemblance to an alligator

Alligator

An alligator is a crocodilian in the genus Alligator of the family Alligatoridae. There are two extant alligator species: the American alligator and the Chinese alligator ....

's or crocodile

Crocodile

A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...

's jaws. Functioning much like a spring-loaded clothespin, the clip's tapered, serrated jaws are forced together by a spring

Spring (device)

A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...

 to grip an object. When manufactured for electronics testing and evaluation, one jaw of the clip is typically permanently crimped or soldered to a wire, or is bent to form the inner tubular contact of a ~4 mm female banana jack

Banana connector

A banana connector is a single-wire electrical connector used for joining wires to equipment. The term 4 mm connector is also used, especially in Europe, although not all banana connectors will mate with 4mm parts...

, enabling quick non-permanent connection between a circuit under test and laboratory equipment or to another electrical circuit.