Ohm’s law states that current flowing through a conductor is directly proportional to the potential differnce across the conducor, provided the temperature remains constant.

I=V/R or R=V/I

Where R is a constant called the resistance of the conductor.

This describes the fundamental relationship between current (flow of electrons i.e.), the voltage (the force that pushes the electrons to move) and the resistance the property of material that will always resist any movement of electrons within it.

Resistance has to be understood as a natural phenomenon. It can be understood from the fundamental laws of motion as enunciated by Newton. the first law of motion is the law of inertia.

There is no normal situation where the there is no resistance to the passage of electrons within any material. And any resistance whether it is pure heat induced resistance to electrons in a (i) DC (direct current) circuit or (ii) by way of opposition to the magnetic field created around the conductor (Lenz’s Law i.e.) or (iii) a creation of a counter electric field as in the case of a capacitor. The last two apply only to the AC (alternating current) circuit.

However, there are now some super conducting materials where the resistance measured is zero for any current, such materials are yet not in commercial production.