Pretty much. You don't want flat beer and co2 gives it the fizz and the foamy head. (que Karl) Like tapping a keg with a hand pump. It will deliver until the captured cor2 is gone then you better start pumping. The c02 is pressure to deliver the beer while providing a foamy head. I put priming sugar in my bottles. The left over yeast eats the sugar and produces c02. I over sugared a batch a couple years ago and when I unscrewed the bottle caps, it oozed foam for 10 or 15 min. :BangHead::BangHead::BangHead::lol: