Kimchi is made through the process of fermentation. First, the vegetables are salted. The salt inhibits the the veggies' ability to absorb water, which makes them crunchier and creates a brine in which the fermentation takes place. Next, spices are added—chili pepper, garlic, etc. Then the mix is left to ferment. The salty water creates a pH environment that's friendly to bacteria that help human digestion. That bacteria feeds on the sugars in the cabbage and releases lactic acid as a by-product. The benefits are then two-fold: the removal of sugars from the cabbage eliminates an appealing food source for destructive microorganisms while the lactic acid creates inhospitible conditions for anything but the "good" bacteria. Plus, the latic acid makes it taste deliciously sour.