Every object or concept can be classified as either digital or non digital, but digital might not mean what you think it does. For example, the earliest TV did not use digital signals. They were analog.
When something is digital there is a finite amount, or limited amount, of possibilities. You see this with modern day computers and smartphones. They are considered digital, because everything you see on your screen is just 0s and 1s in different orders, sending signals to tell your device what should be shown.
Analog is the opposite, it is infinite, meaning there is an unlimited amount of possibilities. This becomes challenging because when there are unlimited possibilities the signal can get messed up. A small glitch will not be able to correct itself because there are an infinite amount of options for what the glitch was intended to be. This is why on old TVs that used analog signals, there was much more static; the signal could not be interpreted correctly. This is called noise and it is the reason why we have mostly moved away from analog systems.
This is the advantage of something being represented digitally, rather than in an analog form, because there is not as much room for error. Without a digital system, we might not be able to send texts, or work collaboratively, or even write papers in a google doc. This is because in an analog system the noise could cause things to change constantly, and there would be no way to monitor this fully or prevent it. Words would get changed and messages would get messed up.
Another example to explain this difference historically is with morse code. Morse code is a way to express letters through either dots (short beeps) or dashes (longer beeps). Morse code is considered digital because there are only two options: dot or dash. This means that when someone sends a message through morse code, it doesn’t matter if the length of a dash is the same every time, because it is distinguishable as a dash. If Morse code was an analog system, a short dash might not get corrected, and could keep evolving into a shorter and shorter dash, eventually resembling a dot, and the message would be wrong.
Now lets break this down and see whether some different objects or concepts would be considered analog, or digital
1. Hieroglyphs = analog
Why? In theory there are an infinite amount of images that could be created
2. Punch Cards = digital
Why? They represent data using binary-like presence/absence of holes.
3. Transistors = digital
Why? They utilize a binary system of 0s and 1s
4. Email = digital
Why? Sends messages encoded by a series of 0s and 1s