A side note: please be forgiving of me because I'm just starting out in Electronics so I'm still confused about certain terms.
Why are optocouplers used?
Yes I know they link a circuit together since there is an LED inside and a photoresistor. I also read that it prevents high voltages. But why use an optocoupler over another component? For example, to reduce high voltages we can use step-down transformers but why, in a certain scenario, we would use an optocoupler over a step-down transformer?
In what scenarios are optocouplers appropriate?
Hope my question is clear enough for anyone who can help.