Analog: Signal that can take on any value in a continuous range (amplitude can be infinite number of values).
- Often confused with continuous time but not the same!
Digital: Signal that can only take on a finite number of values.
- For example, a binary signal is digital because it can only take 0 or 1.
- Often confused with discrete time but not the same!
Continuous Time and Discrete Time Signals qualify the nature of the signal along the horizontal (time) axis. Analog and Digital qualify the nature of the signal amplitude (vertical axis).