Atoms are composed of protons, neutrons, and electrons. The forces of attraction between the electrons and the protons hold an atom together.
Electrons have a negative and protons have a positive electrostatic charge. Like charges repel, unlike charges attract, just like with magnets.
The valence shell is the outer shell of the atom. Some materials have a free electron in the valence shell and this electron can easily move from atom to atom. It is the free electrons that are responsible for electrical current.
Materials that have free electrons and allow electrical current to flow easily are called conductors. Common conductors are copper, aluminum, gold, and silver.
Materials that have free electrons but do not share them easily are called insulators. Common insulators are glass, air, rubber, plastic, and wood.
Electricity is a term used to describe the energy produced (usually to perform work) when electrons are caused to flow directionally (not randomly) from atom to atom. The movement between atoms is called electric current.
Current is measured in units called amperes or amps. Amperage is a term used to describe the number of electrons moving past a fixed point in a conductor in one second.
EMF is electromotive force. It causes the electrons to move in a particular direction. Without electromotive force the free electrons of atoms would move in random directions. EMF is measured in volts.
Wires and various components connected together form a circuit. When all the components are in line with each other and the wires, a series circuit is formed. When some of the components are connected parallel with each other, they form a parallel circuit.
A load is any device in a circuit that is using the energy that the electron current is delivering to it, i.e., our homes and businesses. The unsightly wires you see crisscrossing our countryside are carrying alternating current from the power plants to the loads.