Final answer:
A punch-down block is a networking component used to connect copper wires together by piercing the plastic sheath of the wire and making contact with metal pins. It helps establish electrical connections between the wires.
Step-by-step explanation:
A punch-down block is a component used in networking and telecommunications to connect copper wires together. It consists of multiple rows of metal pins, usually 25 rows of four pins each. When a wire is pushed into a pin, it pierces the plastic sheath of the wire, making contact with the metal pin. This process is known as 'punching down' and helps establish electrical connections between the wires.