barley is grown, harvested and dried
hop flowers are grown, harvested and dried
barley is malted and cracked
hot water extracts fermentables
runnings are made into wort
hops added here and there
transferred to a fermenter
yeast takes up residence in the wort
carbon dioxide created along with other things
What function does the carbon dioxide serve in the fermentation vessel?
Edit: To read my attempt at answering this read this.