I tried looking it up, and my brain just wasn’t making sense of it, but I haven’t had coffee yet so.
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Analog refers to continuous signals whereas digital has discrete values. For instance an analog radio would have the actual signal modulating the carrier whereas a digital radio would have ones and zeroes encoded on the carrier which represent the actual signal.
A digital system has distinct states things can be in. A computer bit can be a 1 or a 0 it can’t be a 0.5. An analog system can have any value.
Digital things can be one of two states. On or off. Yes or no. 1 or 0. Analogue can be anything in between.
Take video game controllers, for example. Modern controllers use analogue sticks. You can push the stick a little bit forwards, and have your character only move a little bit. The controller knows the difference between pushing a little bit and pushing a lot, because it’s an analogue input. A digital input would be simply on or off. Is the stick being pushed, or is it not? Buttons are a good example of this. You get a modern controller and press the X buttons, it only knows if you’re pressing it or you’re not, it doesn’t matter how hard you press it.(*)
Let’s use music as an example. Vinyl records use shapes of grooves which are converted to sounds, an analogue format. If there’s a speck of dust on it, that will change the sound. A CD meanwhile is a digital format, it’s just a lot of 1s and 0s being read by a laser, which are translated to music.
(*) The PS2 and PS3 actually have analogue face buttons, where pushing harder does register as a harder press. So does the original Xbox too I believe. But most controllers don’t.
At its most basic, analog means something has some kind of spectrum or range, and digital means it can only have certain (“discrete”) settings.
So analog is like an old radio dial, you can set it to 1, or 2, or 1.5, or 1.9736, or any other value you want on the dial.
And discrete is like a light switch, or the pullstring on a ceiling fan. It can be set to “Off”, “Low”, or “High”, but it can’t be set to any intermediate value between those options.
A light switch is digital. It can either be off and on, but nothing in between. A light dimmer is analog. It can be in any state ranging from fully off to fully on.
The clever thing about digital electronics is that it can pretend to be analog by switching on and off extremely fast and/or in complex ways. This pretending is often more accurate than trying to keep an analog system in the exact required state. An electronic component may be a little more conductive when it gets hot, for instance, meaning that adjusting its conductance precisely in all conditions is a difficult task, but switching it rapidly off and on, so that the average conductance looks the same, is much easier. This, plus the fact that digital electronics can be tricked into doing enormously complex math with pinpoint accuracy, is what has lead to the domination of digital technology.
Edit: we may well be heading for an analog revolution, because we have recently been tricking enormously complex math into doing things the way brains do, by pretending to be somewhat analog. If we can make a machine that *is* analog and does the same thing, it can potentially be much quicker.
Analog comes from analogous.
> comparable in certain respects
So if the representation of something is comparable to the actual thing, it’s analog.
For example, a vinyl record is an analog recording of sound. The wiggles in the grooves of the record are the exact same wiggles of the actual sound wave. The grooves are a representation of the sound, and they’re directly comparable to the actual sound waves. The grooves are *analogous* to the actual sound waves.
Meanwhile, a CD is a digital recording of sound. A CD has a bunch of pits and lands (aka 0s and 1s) etched into it. Not at all comparable to an actual sound wave. You need a key to decode it to get the actual sound wave information out of it. The pits and lands are not analogous to the actual sound waves.
Analog uses continous signals, while digital uses discrete signals. Continious values are like waves in physics, so they have infinite resolution (possible values within some range) at cost of being imprecise (there’s always some error as with quantum systems). Digital ones, on the other hand, have limited set of values, but do not suffer from measurement errors. Our world is actually analog, so digital circuits are just kinda built on top of that like normal physics works on top of quantum theory.
This Veritasium video has a great explanation and some fascinating examples
Let’s say you want to send a message by changing the voltage over a wire, kind of a telephone. You speak into a microphone, which varies voltage over a line, which is fed into another speaker that reproduces the speech. But any noise on the line, especially over long distances, will mean the voltage isn’t received as it was sent, and the message quality will be poor.
But think of Morse Code, which really was digital. It was sent as voltage over wires too, but either power is applied, or it isn’t, so it was very tolerant of line noise. Words were encoded into an on-off format, sent over the wires, and then the on-off format was reconstructed into words.
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