How to Understand resonant frequencies

In this video tutorial the instructor demonstrates resonant frequency. In this video the instructor shows the sound of resonance and how to generate it. Resonance is a forced vibration of energy into molecules of an object that makes those molecules vibrate at their resonant frequency. When these molecules vibrate naturally they produce a kind of noise that can be annoying some times. In this video the author makes a small object using a rubber band and a net that produces vibrations when rotated and causes that irritation resonance sound. This video shows what resonance is and how to produce it naturally.