The wire on the charger that came with my laptop eventually frayed, and I had to buy a new charger for my laptop. Both the new and old chargers for my laptop plug into a standard wall outlet. On the new charger, it says the following: " Input: 100-240V ~ 1.5A 50-60Hz Output: 19V --3.42A 65W MAX. " I assume that the V stands for voltage, and the A stands for amps. But why is there a different voltage for input and output? What is the meaning of input and output? Why is there a different amperage for input and output?