Definition: "A potential difference of 1 volt exists between two points if one joule of work is done in carrying a unit positive charge from one point to the other point."
I know that the standard definition above is not easy to understand.
Read on the explanation below.
Voltage is just the driving force which causes the current to flow through the circuit.
Imagine a footballer is running with a football. If the speed of the football is current then the force supplied by the footballer with his foot is voltage.
The most general and basic answer that a common man(other than an Electrical Engineer) can give is
Potential Difference:- "The difference between the potential of two charged bodies is called potential difference", which is as true as any other definition. Hence we see that a common battery or cell has a '+' terminal and a '-' terminal. This is to create a potential difference between the two battery terminals and this potential difference is responsible for the current flowing through the circuit in which the battery or cell is connected.
If we go into the chemistry of the subject then:-
We know that generally free electrons are required for current to flow through a material. There are no free electrons in insulators (eg: wood, plastic, pvc compound, XLPE, procelain etc) hence they act as insulators and doesnt allow current to flow through. But, if a high voltage or high potential difference is applied across that insulator material then its valance electrons gets the required ionization potential and becomes free electrons. This is called insulation breakdown in our terminology.
