Answer: That's a pretty broad question, don't you think? But every note has a corresponding rest that takes up the same amount of time - except that of course a rest is the opposite of a note - it's a moment of silence.

Rests are important, though. You count them in your mind just like notes; the hidden rhythm of the music continues to beat right through them; they are as definite in time as notes are. They say time is nature's way of keeping everything from happening all at once; rests are how we measure time between note events.

Here's a chart showing the rests and their corresponding note values; a similar chart can be found on page 13 of Exploring Theory with Practica Musica: