How Do Speakers Work?

In any kind of sound system structure, the best quality of sound which can be obtained is dependant on the speakers. The best system will sound horrible if it is hooked up to bad speakers. The working of a speaker itself is pretty simple, but it has many important aspects which are beyond the realm of this discussion. First, let's start with the basic concept of sound, to help you understand better:

To simply put it, one can hear due to the vibration of the eardrum which the brain interprets as sound. The same principle is applied in transmitting sound through speakers. Basically when a substance vibrates, it automatically moves the air particles surrounding it. Let's take an example of a bell. On ringing a bell, the metal vibrates, causing the particles to be pushed on the opposite side, colliding and resulting in sound.

For a comprehensive explanation of how speakers work, go here - electronics.howstuffworks.com.