A crimping tool is a device used to conjoin two pieces of metal by deforming one or both of them in a way that causes them to hold each other. The result of the tool's work is called a crimp. A good example of crimping is the process of affixing a connector to the end of a cable. For instance, network cables and phone cables are created using a crimping tool (shown below) to join the RJ-45 and RJ-11 connectors to the both ends of either phone or CAT5 cable.
How does it work?
To use this crimping tool, each wire is first placed into the connector. Once all the wires are in the jack, the connector with wires are placed into the crimping tool, and the handles are squeezed together. Crimping makes the plastic connector puncture and hold each of the wires, which prevents the wires from falling out, and allows for data to be transmitted through the connector to each of the wires.