What is Voltage?
Voltage is the difference of electrical potential between two points or two objects, expressed in volts. Without this difference of electrical potential, electricity could not be used as a power source.
Electricity flows through devices in either Direct Current (DC) or Alternative Current (AC).
The domestic mains power supply in Australia is 240V AC, 50Hz.
However, although Alternating Current (AC) is the most efficient way to deliver power, many low voltage electronics (e.g. LEDs) need Direct Current (DC) to function.
For this reason, a transformer might be needed to convert the AC voltage to DC.