Benjamin Franklin’s most important find was that all electrical capacities are not equivalent. Instead, they retain one of two opposite charges, which has become the basis for the "plus" and "minus" terminology that is still used today. An understanding of positive and the negative charges helped to identify atmospheric and frictional electricity.
Franklin’s work became the basis for the "single fluid" theory. This theory states that when something is being charged, electricity flows from a positive body with an excess charge to a negative body with negative charge. He proved that electricity is "fluid," meaning it can pass from one body to another.
Franklin invented many of the electrical terms that are still used today. At the time, Franklin felt that there were insufficient words to describe his observations and discoveries. Therefore, he created a new nomenclature that included words like charge, condenser, conductor, battery, plus, minus, positive and negative.
During his experiments, Franklin built an electrical battery, roasted a duck on a spit powered by electricity, sent a current through water to ignite alcohol and ignited gunpowder. He also came up with the idea of using an iron rod to attract lightning bolts and protect buildings from lightning strikes. This invention is now called the lightning rod.