There are three main reasons why people snore:
Firstly, the sleeping posture. Sleeping on your back can cause the weight of your neck or your chest to press down. As a result, your airway collapses, blocking the airflow when you breathe, resulting in snoring.
Unhealthy lifestyle may contribute to snoring problems too. Being overweight or excessively smoking and consuming alcohol would narrow your throat and decrease the muscle tone. A narrower airway can result in more vibration as you breathe, producing the snoring sounds.
Lastly, having allergies like sinus or other nasal problems may cause your airway to be blocked, thereby resulting in more vibration and creating snoring sounds. In a worse condition, you might behaving obstructive sleep apnea (OSA), a condition that blocks the throat and literally stops you from breathing while you're asleep.