Ben Franklin did not invent electricity, but he did gain some understanding about it that people previously did not know. His initial hypothesis was that it contained a common element, which he dubbed as electric fire.
Eventually, Benjamin Franklin's theories about electricity were named the single fluid theory. In the case of charging a battery, the single fluid theory states that electricity flows between the positive and negative. These are denoted by plus and minus signs, which can also be found on other things that conduct electricity. During his experiments, Franklin coined a number of terms, including "conductor," "condensor," "armature," "battery" and "charge."