Electricity results from the flow of enormous numbers of tiny particles called electrons. Electrons are one of the two kinds of charged particles in atoms, which make up matter. The other charged particles are called protons. An electron has a negative charge and a proton has a positive charge. Positive and negative charges attract each other. However, two positive charges, or two negative charges, will push each other away. In other words, like charges repel, and opposite charges attract.

Over the years scientists learned how to use the electrical forces that charges exert on each other. They were able to get large numbers of electrons to flow in loops, called circuits, through wires and then through devices that do useful tasks. The moving electrons are called a current. The electric currents used for lighting, heating, and driving machinery are made by machines called generators. Generators cause a current to flow by moving a magnet past a coil of wire. Electric current can also be produced by a chemical reaction in a battery.

The ancient Greeks were the first to study electric charges and forces. In the American colonies during the 1700s, Benjamin Franklin performed experiments that proved that lightning is a form of electricity. Also in the 1700s scientists realized that there were two opposite kinds of charges. Not until the late 19th and early 20th centuries, however, were electrons and protons discovered and measured precisely. Today electricity provides most of the energy and power to run the modern world.