How run across electrons from one place in another? The answer to this question will slightly open one more particle of an electric mosaic. To move, electrons use so-called conductors. Thus, the electricity represents no other than the directed movement of electrons in the conductor.
The set of materials can act as conductors, but one of them it is more preferable than others. Electrons move much easier on metals, than on plasticity. In general, though in plastic they also will move round the friends of protons, where it is more pleasant to them to stay at home, than somewhere to run. But in metal electrons are free to move where will want. It is possible to draw an analogy between free electrons in metal and the stones thrown on ice. Electrons slide through metal, as on ice. And here plastic — an insulator — reminds sand more: stones hardly will move far from that place where fell, as well as electrons in plastic.
So what materials represent good conductors, and what — good insulators? Usually as conductors use copper and aluminum (is more often — copper). And plastic and glass, as a rule, act as insulators.
As measure of ability of electrons to move on a material resistance serves. The copper wire of big diameter has the smaller resistance to a stream of electrons, than a wire from the same copper, but smaller diameter. You should understand properly for yourselves sense of resistance because each project connected with electronics, includes resistors. Resistors call elements with a certain resistance which helps to supervise a stream of electrons in conductors.