WAVES: harmonics

Animation of harmonics: illustrating how an oscillator (such as a guitar string) can vibrate at different frequencies. In reality, all of these vibrations would be happening in the same string, but they are separated out for clarity. The lowest frequency (in red at the bottom) is called the fundamental frequency. The still points or nodes (orange balls) occur at points where the troughs and peaks cancel each other out (as a result of interference, which is how standing waves are created).