Introduction

Snoring is the act of breathing through the open mouth in such a way as to cause a vibration of the uvula and soft palate, thus giving rise to a sound which may vary from a soft noise to a loud unpleasant sound. This most commonly occurs during sleep.
The cause of snoring is some kind of blockage in the breathing passage. Those blockages can be of many kinds—here are just a few:
Tongue falling into the throat
Allergies
Throat weakness causing the throat to close during sleep
Mispositioned jaw, often caused by tension in muscles
Fat gathering in, and around, the throat
When the airflow in the breathing passage becomes irregular (because of the blockage) then the soft palate starts flapping. This flapping of the soft palate is what makes the snoring sound.