Before you can do much that's very interesting with electronics, you need to have a basic understanding of what electricity is and how it works. One of the basics of electricity — and therefore, electronics — is the concept of electric charge.

Two of the three particles that make up atoms — electrons and protons — have a very interesting characteristic called electric charge. Charge can be one of two polarities: negative or positive. Electrons have a negative polarity, while protons have a positive polarity.

The most important thing to know about charge is that opposite charges attract and similar charges repel. Negative attracts positive and positive attracts negative, but negative repels negative and positive repels positive.

As a result, electrons and protons are attracted to each other, but electrons repel other electrons and protons repel other protons.

The attraction between protons and electrons is what holds the electrons and the protons of an atom together. This attraction causes the electrons to stay in their orbits around the protons in the nucleus.

Here are a few more enlightening details about charge:

• Charge is a property of one of the fundamental forces of nature known as electromagnetism. The other three forces are gravity, the strong force, and the weak force.

• An atom normally has the same number of electrons as protons. This is because the electromagnetic force causes each proton to attract exactly one electron. When the number of protons and electrons is equal, the atom itself has no net charge. It is then said to be neutral.

However, it's possible for an atom to pick up an extra electron. When it does, the atom has a net negative charge because of the extra electron. It's also possible for an atom to lose an electron, which causes the atom to have a net positive charge because it has more protons than electrons.

• If you've been paying attention, you may have wondered how it can be that the nucleus of an atom can stay together if it consists of two or more protons that have positive charges. After all, don't like charges repel? Yes they do.

But the electrical repellent force is overcome by a much more powerful force called, for lack of a better term, the strong force. Thus, the strong force holds protons (and neutrons) together in spite of the protons' natural tendency to avoid each other.

• The strong force doesn't affect electrons, so you never see electrons clumped together the way protons do in the nucleus of an atom. The electrons in an atom stay well away from each other.

• If one were so inclined, one might liken the strong force to the patriotic force that binds the citizens of a nation together in spite of their differences. It's this force that keeps a country together in spite of the fact that its political parties seem to hate each other.