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Some elements don’t hold on to their outermost electrons very tightly. These elements frequently lose electrons or pick up extra electrons, and so they frequently get bumped off of neutral and become either negatively or positively charged. Such elements are called conductors. The best conductors are the metals silver, copper, and aluminum.

Other elements hold on to their electrons tightly. In these elements, it’s hard to pry loose an electron or force another electron in. These elements almost always stay neutral. They’re called insulators.

In a conductor, electrons are constantly skipping around between nearby atoms. An electron jumps out of one atom — call it Atom A — into a nearby atom, which I’ll call Atom B. This creates a net positive charge in Atom A and a net negative charge in Atom B. But almost immediately, an electron will jump out of another nearby atom – call it Atom C — into Atom A. Thus, Atom A again becomes neutral, and now Atom C is negative.

This skipping around of electrons in a conductor happens constantly. Atoms are in perpetual turmoil, giving and receiving electrons and constantly cycling their net charges from positive to neutral to negative and back to positive.

Ordinarily, this movement of electrons is completely random. One electron might jump left, but another one jumps right. One goes up, another goes down. One goes east, the other goes west. The net effect is that although all the electrons are moving, collectively they aren’t going anywhere. They’re like Keystone Kops, running around aimlessly in every direction, bumping into each other, falling down, picking themselves back up, and then running around some more. When this randomness stops and the Keystone Kops get organized, the result is electric current, as explained in the next section.