Analog or analogue is an electronic communication sent as signals of varying frequency instead of ON or OFF like a digital data transmission. Analog allows equipment to handle information that continuously changes such as voltage, current, and wave.
The picture to the right is an example of an analog signal or how analog may be represented. In the example of a wave, it has a high and low value with numerous values in-between. With a digital wave, it would have a high or low value (on or off), with nothing in-between.