What is the difference between an "analog" and a "digital" signal?

What is the difference between an "analog" and a "digital" signal?

TJ McClearin (Business Manager, Infinity Wireless, LLC) gives expert video advice on: What is "bandwidth"?; What is "broadband"?; What is "roaming"? and more...

The difference is, is that analogue is the exact wave. Because when sound is created, it's created in the wave format. Digital however, takes that wave and approximates it. So digital is making guesses as to where the next point should be on the wave and by doing so you don't get as clean as sound with digital as you would with an analogue signal. However, there's less data being transferred by a digital signal because the approximations can be compounded into smaller pieces of data.