Good singing is the result of good breathing.
Breathing is very important because it helps improve your vocal sustainability. An abundant supply of air with regulated outflow will help you sing sustained notes with ease.
Breathing is simply the inhalation and exhalation of air. Normally, when we inhale we feel that our stomach contracts and when we exhale, we feel that our stomach expands.
You see this is not logical. Let me explain. Consider your car tyre. When you inflate it, the tyre expands; when the tyre is flat (no air), it contracts.
It should be the same as our stomach. When you inhale, it should expand and when you exhale it should contract.
This is the right approach to breathing in preparation for your singing.
Ben's Vocal Music Tips 