I’m new to digital electronics and try to understand how logic gates works.

In books many times Zeroes​ and ones are referred as Low and High respectively, is Low and High used as an indication of lower input voltage and higher input voltage ?

And if Zero used as a low input voltage then isn’t no input can also be considered as Zero by default?

or it depends on how the gates are implemented (e.g – AND gate can be implemented using diodes or transistors) and so in some cases no input by default is same as Zero input while in others they are different ?

I’ll thankful if anyone can explain these things using an easy example !