Analog vs. Digital Signals

When it comes to electronics, there are two major types.  Without one, electronics as a whole will become obsolete.  Analog signals require a range of numbers.  This can be anything from how much light a sensor receives, the distance an object is from a sonar or how warm it is inside a room.  The size and magnitude of the number depends on the sensitivity of the sensor in question.  When graphed, the analog signal can have many different slopes, heights, different peaks and different low points.  When graphed the line should be a smooth continuous line, most similar to a sin curve. Digital signals are either on or off.  For example, a light switch is a digital device, either on or off.  When graphed, digital signals appear blocky, either at a high point or at a low point.  Digital signals are the ones used when logic gates are placed in a  circuit.  This is because a on or off is required in the gate, and if the gate received a numerical input like 5234, the gate would have no idea what to do with it.  Digital is used for computing and digital electronics while analog is better for video and audio signals.  It is important to understand that analog deals with ranges of numbers, and digital deals with a definite binary bit, this makes digital somewhat easier to predict the outcome.  This is because with digital, you can predict what ALL the possibilities are with a truth table.  With analog, it can sometimes be difficult to predict what the sensor will output. 

Here are some links to check out to learn more!
https://learn.sparkfun.com/tutorials/analog-vs-digital
http://www.diffen.com/difference/Analog_vs_Digital