T-money, Naver Maps, and the K-ETA question

Buy a T-money card at any convenience store; it works on subways, buses, and taxis nationwide and in shops. Google Maps barely works for directions in Korea; use Naver Map or Kakao Map, both with English settings. Many visitors need a K-ETA travel authorization before boarding, though exemptions have been extended for some countries; check the official K-ETA site. Cards are accepted almost everywhere, including street markets.