Breath support is the basis for everything in singing. If you do it properly you should have zero tension in your throat. It’s also the reason you can make a sound in the first place because without moving air, there’s nothing to vibrate the vocal cords.
How to breathe when you sing. Step one. Breathe in and RELAX your stomach. That means the stomach should move outwards when you breathe in. You may have to really work on this because we often hold our stomach’s tight all day long. But the wall of the abdomen is the only way we can control the diaphragm, so as we breathe in we’re setting up the process where we will control the air later on.