Most musicians know a bit about “delay”… not like… my flight is delayed…. but the music kind.
For example, your guitar player might have a Boss DD-3 Pedal or your vocalist might like delay on his/her vocal. If you’re not a musician, think of this as echo. The basic premise is a repeated signal with decay over time. The time interval (speed), amplitude (volume), and feedback (how quickly the delay dissipates) are variables of modern delays, but they also happen naturally.
These are some examples of natural delay:
Now, if you lived before the 1950’s, these kinds of things were your only option for recording a delayed signal. Worse, you would likely be trying to record to a metal wire or some such nonsense so why not load your sherpa up and get your session started. America didn’t even know about magnetic tape until we took it from the Germans after WWII.
Luckily, these days we can get our bands down off of the mountain. Thanks to some real music geniuses, we have delay at our fingertips in every studio and stage on the planet.