A crimping tool is used to connect connectors like RJ-45 and RJ-11 to the end of cables. The tool crimps the connector to puncture and hold the wires in place. The document provides details on the crimping process, including wire color schemes, steps for crimping RJ-45 connectors, and ensuring a proper connection by testing the cable. It explains that crimping involves inserting wires into the connector, crimping it with the tool, and testing to avoid issues from miswiring.