distribution of current

Sheldon()

Can someone explain me how the electrons flow from power plants to our homes when they change their directions all the time? I know that this is stupid question but i am confused for some simple staff. What a socket represent? I know that socket is like voltage generator,but current is all the time flowing in the wire behind the wall or standing still and when the device is attach to the socket its starting to flow?And one more thing, the other wire with the hot wire in the socket is neutral,this one is without polarity but when device is attach is there some polarity in this wire?