Start with the exact terminal, not just the city
Korea has separate express-bus and intercity-bus networks. A city can have more than one terminal, and a route to the same region may leave from a different terminal depending on the operator or bus type. In Seoul especially, terminals are far enough apart that going to the wrong one can mean missing the departure.
Express and intercity are not interchangeable labels
Express buses generally connect major cities on longer corridors, while intercity buses often serve a broader mix of regional cities, counties and smaller terminals. For a traveler, the practical rule is simple: use the terminal printed on the ticket or booking screen, not the terminal you used on a previous trip.
Booking from abroad
Korea Tourism Organization's current transport guidance points foreign visitors to multilingual booking options for express and intercity buses, including Hanpass and selected third-party channels. Availability, supported payment cards and route coverage can differ by platform, so confirm the final terminal, departure time and refund rule on the booking screen before paying.
At the terminal
Arrive with enough time to find the correct platform and check whether you need a paper ticket or can board with the issued mobile/QR ticket. On-site counters and ticket machines remain important fallbacks, but language and foreign-card support can differ by terminal and machine.
The last bus is only part of the plan
A long-distance bus may deliver you to a county or city terminal after local buses have become infrequent. For rural, coastal and mountain destinations, check the onward local bus or taxi before choosing a late arrival. The long-distance ticket solves the intercity leg, not necessarily the final few kilometres.