Perhaps the best way to describe analog is to compare it to digital. A digital signal, simply put, will look like intermittent bursts of energy. The energy is either present or there is none. An analog signal, on the other hand, is a continuous wave that either rises or falls depending on the amount of input.
Analog is used in applications that need to measure a steady stream of inputs. For example, most speedometers in cars are analog. They constantly measure a vehicle’s change in speed, which is a continuous input for as long as the vehicle is moving.
Other interesting terms…
