Zinc-Copper Electrochemical Cell Demonstration

What do you need to make an electrochemical cell?
This video demonstrates that a voltage is produced between pieces of zinc and copper when they are both placed in solutions containing ions. The zinc and copper half-cells are connected by a salt bridge, which allows ions to flow between them.
The video finishes with a discussion of the sign of the voltage produced, which depends on the choice of terminals on the voltmeter which the half-cells are connected to.