Korea's national dish, kimchi, comes in many, many different styles and varieties. The only universally accurate way to describe it is, perhaps, as a pickled vegetable dish. The type of kimchi that most people will likely recognize is made with Napa cabbage and spicy red chili flakes.
Contrary to popular western belief, kimchi is not made from food that has been buried underground - that is, not anymore. Since modern technology now provides us with shelter from the heat of the sun, most people just let their kimchi ferment on the counter or in the fridge.
Another myth about kimchi is that it always contains fish. Although seafood ingredients are often popular in many types of kimchi, every type I've ever found at a grocery store has been vegan. I've found vegan kimchi in the refrigerated produce sections of asian markets, natural food stores and conventional groceries. That said, I don't buy my kimchi at the store anymore since I learned out how fun and easy it is to make at home.