A logic gate is an idealized model of computation or physical electronic device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output
This is actually how the underlying not gate is implemented.
Multiple Input Logic Gates
These two are universal gates.
XOR and NXOR Gates
Logic Gates from Hardware
This is the part that I actually need to understand. Learn from Ben Eater.
And Gate using transistor
Not Gate using transistor