The first microphones were invented in the course of developing the telephone, a fact that's overlooked by many people but obvious when you think about it. Since then, microphones have come to be used in all manner of technology, from making records to performing live music, from dictaphones to personal computers.

Many devices such as tape recorders, video cameras and even some computers have built-in microphones. Other devices require external microphones, and even things with built-in mics often produce better-quality sound if an external mic is used.

There are five basic types of microphones, each using a different technology.

The first kind of microphone used carbon dust and little diaphragms to convert sound waves into electrical signals. Dynamic microphones use magnets to produce the same effect. Ribbon microphones use thin ribbons suspended in magnetic fields. Condenser microphones function as capacitors, often requiring a battery to create voltage. Finally, crystal microphones make use of the unique electrical properties of some crystals.

When it comes to personal computers, microphones can be handy for certain applications, though most users don't consider them a necessity for everyday computer usage. Some instant-message programs allow you to actually speak to the other person, provided both of you have microphones. Some people use their computers as miniature recording studios and thus need microphones to record their voices. And of course with podcasts becoming more and more popular, computer microphones are even more in-demand.

Microphones vary widely in price and quality. The cheapest ones start at around $20 for very basic, imprecise use. The most expensive ones can be several hundred dollars for intricate, state-of-the-art quality. Musicians' technicians often speak passionately about the brands and types of microphones they prefer, knowing their differences inside and out. To the average listener, though, they all sound about the same.