To understand the basic power terms, think of the analogy: "Power flows through a cable like water flows through a hose." Volts (V) measures the power "pressure" in the circuit. Just like water pressure varies from house to house, power pressure (voltage) varies from application to application and from country to country. Some applications or countries require low power pressure (120 V for example); others require higher power pressure (230 V for example), and so on. One pressure is not better than another, just different. Amps (A) measures the "volume" of power flowing through a circuit, just like "gallons" or "liters" measure the volume of water flowing through a hose. Pressure and volume are important, but ultimately the user will need to find out the total power volume required to run an electrical device. Once the value is discovered--which is measured in Watts (W)-- one will be able to recommend one or more Tripp Lite UPS systems that have enough capacity to accommodate the devices. Incidentally, when measuring large power volumes, kilowatts (kW) is used, which are increments of 1,000 watts.