What actually is voltage

Uniontera number 12, hope it helps.

Existence is the time expressed by light itself. http://www.youtube.com/watch?v=MjmOw1Pnc…

There's not really a one line answer here. Google "voltage" and even Wikipedia has a pretty good definition.

If you can't explain it to a six year old, you
don't understand it yourself.”

There are many things a six years old boy dont understand. when einstein was at six he was not surely aware of relativity.

Even einstein never explained his relativity to 6 years old boy.

Age is not important and how mature your brain is important.

Probably you are more confused.

1). Take a simple copper wire. I know copper wire has lot many electrons. but still i dont get bulb glowing if I attach it to bulb.

Clearly we need electron running. What do you mean by running electron.Running electron means having some energy with it. Hope clear.

?but what is voltage. is voltage the concentration of electrons on one end which have the potential to move to the other positive end.?

In every conductor there is a hell lot of concentrated electrons. but why dont they produce voltage?

Answer is Equilibrium. All these electrons are in electrical equilibrium. Equilibrium is a state where electrons mutually interact. Clearly this equilibrium gives rise to equi potential state.

It is like a bucket of still water. it does not flow. but still it can flow.

So clearly we need to destroy the equilibrium. To destroy equilibrium, we supply some energy(mechanical, thermal or whatever)

Equilibrium itself holds some fixed amout of energy with in it so you need to offer more energy.

That means you kick the equilibrium with an electron which is more powerful than the one in equilirium.