Question

why is kimchi fermented

Answer 1

The process that turns vegetable to kimchi is called “Lacto-fermentation” – a transformation process by Lactic Acid Bacteria (LAB). The bacteria metabolizes carbohydrates (such as sugar) in vegetables into lactic acid, which gives fermented foods their sour flavour and increases their acidity, making them safe to eat

that's why kimchi is fermented.