Salt sucks out the liquids from your cabbage and helps it to preserve. So, the shredded cabbage needs to be salted layer by layer and stomped down, that way the salt is spread out and gets u0022activatedu0022 and the fermentation process begins in the anaerobic environment (closed lid, no fresh oxygen). The Oxygen is replaced with CO2 and other gases and the sugars in the cabbage are fermented. Bacteria do all the work here and it leaves you with beautiful Sauerkraut!