These are combos of numbers and letters that are given by a casino's affiliate sites to show that a user has satisfied reward terms. Users enter them on the casino site to claim bonus bets and spins. This means that they can get to play some casino titles without using their own money.
South Korea is an East-Asian country occupying the southern half of the Korean peninsula. It is known for its green hilly landscape that is dotted by cherry trees and ancient Buddhist temples. This is in contrast to high-tech cities, such as Seoul. Gambling is illegal in South Korea, but many Koreans play in foreign online casinos.