To make sense of voltage, we will need to make an analogy.
Lets imagine that electrons are represented by a marble on a flat plane. At this point, the plane is level and the marble does not move. If the plane is lifted at one side, the marble will roll down to the lower point.
In electricity, the high point is a point with lots of electrons and the low point is a point with a lack of electrons. The high point is called the high potential and the low point is the low potential. The difference between these two points is called the potential difference. The larger the potential difference, the larger the voltage.
Voltage can be thought of as the measure of the pressure pushing the electrons. The higher the pressure, the higher the voltage.
Voltage is represented by the letter E. The basic unit of measure is volts or the letter V. One volt will push 1 amp of current through 1 ohm of resistance. Resistance will be discussed in a later section.