http://www.diffen.com/difference/Analog_vs_Digital

Difference between Analog and Digital signals

There are two type signals in digital media studies which are analog and digital signals. Analog and digital signals are used to transmit information, usually through electric signals. An analog signal is any continuous signal for which the time varying feature (variable) of the signal and digital signal uses discontinuous values. Example the classic clock and electronic clock. According to the classic clock, when the pointer points on between two dots, you cannot tell the exactly value because you don’t actually see the number between it. You can predict  approximate number that you can see on the clock but not decimals. Since you can’t tell the exactly value so the classic clock is an example of analog signal. Electronic clock gives the exactly value of time by showing on screen, so this is called digital signal.