So im a baritone with d2 to c5 or d5(not sure yet because im still struggling in high notes). In one of my recent classes i might have realized something but not sure yet. I used to use my head voice after e4/f4 and fail to hit a4 let alone b4 but when i tried to sing from g4 to c5 without head voice it was more stable. At that point i also start to feel how head voice feels in my body and realised i might have used head voice in lower notes accidently and didnt realize back then; judging by how those notes sound and felt in my body. My question is; is head voice there to go past your comfortable zone or it can be used in your comfortable zone? What exactly is head voice for?