ATOMS AND MOLECULES:
As we know, everything in the world, whether solid, liquid, or gas, is made up of atoms. Each atom contains some number of electrons, protons, neutrons, and other sub-atomic stuff. The nucleus (central region) of each atom contains the protons (positive charge) and neutrons (no charge). Electrons (negative charge) live in a cloud around the outside. Since electrons and protons are charged particles, each atom prefers to have the same number of electrons as protons.
Atoms of one or more types are organized into molecules. There are only a hundred or so types of atoms, but there are an almost infinite number of different molecules. Molecules are the building blocks from which all real objects are made.
Molecules are not always so simple. Some organic molecules (like those in our bodies) can comprise hundreds of atoms.
Every atom has its own complement of electrons. In a conductor, some of those electrons can jump from atom to atom. But electrons don't move from atom to atom without a reason. When electrons are flowing there is always an electrical force pushing them along. We called this force as "Voltage".
Are Voltage and Current Related?
Voltage and current are not the same thing, although they are closely related. In simple terms, Voltage causes Current. Given a Voltage and a path for the electrons, current will flow. Given the path, but no Voltage, or Voltage without the path, there will be no current.