Australian, UK, US and most western European citizens receive a 90-day entry permit on arrival.
Most likely you’ll arrive at Incheon International Airport. If you're travelling from within Korea, your arrival point could also be Gimpo International Airport, or Seoul or Yongsan train stations, or one of the long-distance bus stations. Ferries to Incheon, west of Seoul, connect the country with China. Flights, cars and tours can be booked online at www.lonelyplanet.com/bookings.
The best price found from United States to Seoul is on September 26th, 2019, travelling with ANA. See more options, compare prices and book: search flights.
You'll definitely want to purchase a T-Money card (also called CITYPASS+) for discounts on bus, subway, taxi and train fares as well as for general convenience. Handy apps for interactive mapping and real-time journey planning across Seoul's transport network include Subway Korea, Kakao Metro/Kakao Bus and Seoul Topis (http://topis.seoul.go.kr).