Current flows from points of high voltage to points of low voltage. Current can be shown in circuit diagrams by using arrows as in Figure 1. The arrow shows which way the current is flowing. An I is usually included beside the arrow to indicate current. Voltage Voltage indicates the power level of a point.
Voltage is measured in volts.
If we continue the river comparison, a point at the top of a hill would be at a high voltage level and a point at the bottom of a hill would be at a low voltage level. Then, just as water flows from a high point to a low point, current flows from a point of high voltage to a point of low voltage. If one point is at 5 volts and another point is at 0 volts then when a wire is connected between them, current will flow from the point at 5 volts to the point at 0 volts. A measurement of voltage is much like a measurement of height. It gives you the difference in voltage between those two points.