Music Theory 101 - Dotted Notes, Rests, Time Signatures and More

From Espie Estrella, former About.com Guide

It indicates how many notes and what kind of notes in a measure. The time signatures commonly used are 4/4 (common time) and 3/4. There is also 5/2, 6/8 etc. The number on top is the number of notes per measure while the number on the bottom indicates what kind of note. Here's a guide:

• bottom # is 1 = whole note
  
• bottom # is 2 = half note
  
• bottom # is 4 = quarter note
  
• bottom # is 6 = 8th note
  
• bottom # is 16 = 16th note